Help and Support

Summary: A glossary of terms relating to John Lewis Broadband and the internet in general.

If you've seen something unfamiliar on one of our pages, you'll find an explanation here in our Glossary.

Choose a section by clicking one of the letters below. All entries are listed alphabetically.

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21CN (21st Century Network)

'21st Century Networking' is a large BT project. The aim is to bring the UK's telephone network up-to-date.

802.xx Standards

The 802 standards define and standardise techniques for networking computers. Nearly all of today's commonly used networking technologies are part of the 802 standard family; some you may have heard of include Ethernet (802.3), Wi-fi (802.11) and Bluetooth (802.15.1).

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The process that puts broadband on your telephone line. All the work is done at the telephone exchange by BT's engineers, home visits are rarely required.

ACS (Auto Configuration Server)

A server that can remotely manage TR-069 based routers. Our ACS server is used to allow our new routers to connect to the internet automatically.

ADSL (Asymmetric Digital Subscriber Line)

The technology we (and most other ISPs in the UK) use to provide broadband. The word 'asymmetric' is used because data moves in one direction faster than in the other.


Software which automatically downloads and displays advertising material on a computer.


Software designed to block or filter spam from your inbox. Due to the prevalence of spam it's rare to find an email service that does not offer an anti-spam solution.


Software designed to protect your computer from virus infection. New threats are found every day so it's important to keep your Anti-Virus software up to date.


An additional file sent as part of an email, commonly used to send photos or documents. Computer viruses can spread as attachments so be careful. Don't open an attachment unless you know and trust the person that sent it to you.

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Bandwidth refers to the amount of data or information that your internet connection can cope with. The more bandwidth you have the faster you can receive data from the internet.

In the context of broadband, bandwidth is usually measured in kilobits or megabits per second (bandwidth can have other meanings in different technical fields).


Bits are the elements of digital data. All letters, documents, sound, images or other information held in digital format is stored and processed as a stream of ones and zeroes. Each individual 0 or 1 is a bit; the word bit is an abbreviation of Binary digit. All measurements of network speed are measured by how many thousands or millions of bits can be delivered or received in a time interval.


Short for web log, a blog is a publicly accessible journal kept on the internet. They can be about any topic that the maintainer (or blogger) wishes to write about.


Term used to describe high-speed internet access. Most commonly offered in the UK via ADSL.

BT Openreach

A division of BT Group who offer LLU and WLR services to telephone and internet providers.

BT Wholesale

Provider of ADSL broadband technology to ISPs in the UK.


8 bits make a byte. Traditionally, a byte is the amount of space a computer requires to represent a single letter, numeral or punctuation point. The size of documents and other files are measured in thousands or millions of bytes.

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When viewing a web site, your browser will store a copy of the site in its cache. This removes the need to download files multiple times and allows sites to be displayed quickly on the next visit. Sometimes when a web site updates, you need to clear your browsers cache before the new content will display properly.

CGI (Common Gateway Interface)

Protocol that allows a web server to connect with external software or servers and generate dynamic content.


Chrome is the web browser launched by Google in 2008.

CLI (Caller Line Identification)

The system used to present your phone number when you make outgoing calls. If you dial 1471 to find out who just called you, CLI is what allows you to get their phone number.


A cookie is a tracking file stored on your computer, used to keep information about preferences or history relating to specific sites. For example, if you are a regular visitor to, a cookie lets the shop remember your name and details of your items.

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An internet connection using a modem to dial into the ISP over a normal telephone line. The speed is limited to 56 Kbps, making download speeds very slow in comparison to broadband. Faster speeds can be attained using ISDN. When dial-up is in use, voice calls cannot be made on the same line.

DNS (Domain Name System)

Used to link domain names to IP addresses, DNS is designed to prevent you having to remember the IP address of each website or server you want your computer to connect to.

For example, if you tell your web browser to go to "" it first contacts a DNS server which replies with the IP address for the domain.

Domain Name

The address that people use to find you or your company online; Type a domain name into your web browser's address bar to go to a specific website. For example, our domain name is


The opposite of upload, when you transfer any document or information from the internet to your own computer this is known as a 'download'.

Download speed

The time it takes for the data you are requesting (a web page, an mp3 etc) to load onto your computer.


A computer program that allows your computer to use a connected device.

DSL (Digital Subscriber Line)

Technology used to provide high bandwidth broadband services over standard copper telephone lines. The most common type of DSL for is ADSL.


Equipment installed in a telephone exchange, essential to providing ADSL broadband to our customers.

Dynamic IP address

An account with a dynamic IP address is given a different IP every time it connects to the internet.

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Ellacoya Networks

Suppliers of the technology that powers our traffic prioritisation system. Ellacoya hardware allows us to inspect, identify and prioritise all traffic on our network.


Short for 'emotion-icons' - these are symbols used in email, instant messaging and text messages to indicate emotions. For example :) is a smile and :( is a frown! (Look at them sideways to see the facial expression.)

Ethernet Cable

Cable used to connect points of a wired network.

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FAQs (Frequently Asked Questions)

A list of common questions and their answers.

Favicon (Favourites Icon)

A small (16x16 or 32x32 pixel) image, displayed in the favourites (bookmarks) list and browser address bar.

File Transfer Protocol (FTP)

A protocol used to transfer data from one computer to another via a network, commonly used to upload web pages.


A firewall is a computer program that acts like a barrier, protecting a computer from unauthorised external access. A firewall is a good way to help protect your system against intruders and viruses.


Area of a website (sometimes a whole website) that hosts discussion and user-generated content. Forums are often separated into different categories (or sub-forums) for ease of use.


A Microsoft program that allows users to design and upload files to a website without the need to code or use other software.

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Before John Lewis Broadband was launched, John Lewis provided broadband services through the Greenbee brand.

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A block of information which appears at the start of every email. Headers identify the sender and recipient of a message, the route the message took from one site to another and the time taken to travel between sites. If your emails arrive late then you can use the headers to determine the cause of the delay.


A configuration file for websites that allows control of advanced features like password protection, error pages, and the ability to show different pages depending on the location of the reader.

Home Phone

Our telephone service, available to anyone with a BT telephone line.


A Hotspot is an area within range of a public wireless network, if you are in a hotspot then your laptop or phone will be able to use the wireless network to connect to the internet.

HTML (HyperText Mark-up Language)

The language used to create most web pages. HTML is a series of instructions which instruct a web browser to display a web page.

HTTP (HyperText Transfer Protocol)

The protocol used by web servers to transfer HTML web pages to your web browser.


Text or images on a webpage that direct you to another webpage (or area of the same webpage) when clicked.

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IMAP (Internet Mail Access Protocol)

A way to check email stored on a remote server. IMAP differs from POP in that it allows you to store messages on the server and manage them from an email program, rather than having to download the messages to your computer.

Internet Explorer

A web browser installed as standard on Microsoft Windows machines. The most commonly used browser in the world today.

IP Address

An IP address is a series of numbers which are used to identify a device connected to a computer network. For computers connected to the internet, an IP address is assigned by their ISP.


A unique identifier given by Nominet to a registrar who handles .uk domains. A domain IPSTAG signifies who is responsible for renewing and managing it.


The wholesale name for the broadband service sold to ISPs by BT Wholesale.

ISDN (Integrated Services Digital Network)

A digital telephone line that provides faster internet connection speeds than ordinary analogue lines. ISDN allows simultaneous transfer of voice, data and video information, but it may soon be made obsolete by Broadband and cable modems, which both provide even faster 'broadband' connections.

ISP (Internet Service Provider)

A company or organisation, such as John Lewis Broadband, dedicated to providing home users and businesses with services such as access to the internet via ADSL, cable or other means.

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John Lewis Broadband

The name of our ISP, providing broadband and phone services.

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Kilobit (Kb)

A measure of computer memory or storage, a kilobit is made up of 1024 bits.

Kilobyte (KB)

A measure of computer memory or storage, a kilobyte is made up 1024 bytes.

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Light User

Some broadband packages are better suited to 'light users'; others are more suitable for those who use broadband services heavily. You may find such a package suitable if you only go online occasionally.


A kernel of a free open-source operating system created by Finnish programmer Linus Torvalds in 1991. Used as the kernel for many free operating systems such as Debian, Ubuntu and Fedora.

LLU (Local Loop Unbundling)

The process where a telephone operator (BT in the case of the UK) allows other providers to use its local network. Providers can then install their own equipment and offer alternative services.

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MAC (Migration Access Code) Key

In the past, you'd need to ask your service provider for a MAC Key to allow you to transfer your broadband to another service provider. As of 20th June 2015 MAC Keys are no longer required to transfer services.

MAC OS X (Leopard, Tiger etc)

Operating System designed by Apple for exclusive use on Apple hardware.

Master Socket

A telephone socket installed at the point where the telephone line enters the property. Any other extensions will be wired into the master socket.

Megabit (Mb)

A measure of computer memory or storage, a Megabit is made up of 1024 kilobits.

Megabyte (MB)

A measure of computer memory or storage, a Megabyte is made up of 1024 kilobytes.


ADSL signals share your telephone line with voice signals. A microfilter is used to separate the two and prevent one from interfering with the other. Each device attached to your line needs to connect via a microfilter, otherwise you may hear interference when making calls, or your Broadband will disconnect when the telephone is being used.

Microsoft Windows (XP, Vista etc)

The most common operating system available today, believed to be installed on up to 90% of the worlds computers.


Modem is an abbreviation for 'modulator-demodulator'; you need one of these to connect to the internet (Broadband or Dial-up). Most routers contain a built in ADSL modem.

Mozilla Firefox

The second most popular web browser after Internet Explorer. Firefox is a freely available open source browser; versions exist for Windows, MAC OS X and Linux.

MX (Mail Exchange) Record

Information held in the zone file for your domain, defines the server that looks after your email. Changing the MX records on your domain will point your mail to a different server on the internet.

My account

Area of the John Lewis Broadband website used to administer your account.

MySQL (My Structured Query Language)

An open-source database system commonly used throughout the internet.

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The rules of internet courtesy. For example USING ALL CAPITAL LETTERS IS CONSIDERED SHOUTING.


Any connection of two or more computers that enables them to communicate.


Unmonitored and open discussion forums on the internet. You can read messages and post messages to newsgroups just like you can with a forum. You can find newsgroups on almost every topic, not just the news.

NNTP (Network News Transfer Protocol)

Protocol used primarily for reading and posting Usenet articles.


Company ultimately responsible for the .uk registry. All public .uk domains (, etc) are managed by Nominet through registrars.

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If you are connected to the internet, you are online.

Open Source

A method of development where the components of a product (the source) are fully disclosed and freely available. Although most commonly associated with software development, anything can be developed using Open source ideals, Open Cola being a good example.

Operating System

Refers to the main software of a computer system, all installed programs run under the control of the operating system.

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p2p (Peer to Peer)

The sharing of files by computers that are connected to a network. Although p2p has many legal uses it's most commonly associated with illegal file sharing.


A unit of information transmitted as a whole from one device to another on a network.


The practice of obtaining personal information by posing as a trusted source.

Phishing emails pretend to be from known and trusted companies such as your bank, phone company or eBay. They will direct you to a convincing replica of that company's site and ask you to enter personal details (log information/account details etc). These details are then stored and used by criminals to access your account as they please.


An open source scripting language used to create webpages with dynamic content.

POP3 (Post Office Protocol)

A protocol used by email software to collect messages from a mail server. Messages are removed from the mail server once downloaded to your computer unless you specify otherwise.


A web site that offers a links to a wide array of resources and services such as email, forums, search engines and on-line shopping.

PSTN (Public Switched Telephone Network)

This is the technical name given to the UK's telephone network.

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Video file format created by Apple. Video files found on the internet are often stored in the QuickTime format, you'll need to install the QuickTime player to view them.

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In the context of broadband, the realm is the bit after the @ sign in a broadband username. For most John Lewis Broadband customers the realm is


A company or body with the authority to register domain names. All .uk domains are registered with Nominet.


A network device that allows the computers connected to it to communicate and share data. In a home network, the router is often built into the same box as the modem, allowing the internet connection to be shared across the network.

RSS (Really Simple Syndication)

A way to publish web site content on websites that update frequently. Content is sent to a feed - to view an RSS feed you'll need an RSS reader.

RSS Reader

Software used to track the content of RSS feeds. Most new web browsers can function as an RSS reader; you can also configure web pages and software on your computer to do this for you.

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Web browser developed by Apple and included with Mac OS X. Also used as the default browser for the iPad, iPhone and iPod touch. Safari was also released for Microsoft Windows in March 2008.

SDSL (Symmetric Digital Subscriber Line)

Similar to ADSL but uses a dedicated copper line with no voice function. The term 'symmetric' is used because the upload speed always matches the download speed.

SMTP (Simple Mail Transfer Protocol)

The protocol used to send mail between servers and from your mail client to a mail server. Our SMTP server address is


Unwanted or unsolicited email that is distributed to huge lists of internet users, usually as part of a marketing or advertising plan. Sometimes it can be dangerous and contain viruses, but standard junk mail is deemed a problem due to the sheer quantity and subsequent time and resource required to deal with it.


Software installed by stealth on a computer and used to track the users downloads, web surfing habits and individual keystrokes. This information is then secretly relayed via a backdoor to an external third-party. Mostly used for advertising and information gathering, Spyware is sometimes used to gather information about email addresses and even passwords and credit card numbers.

Static IP Address

An account with a static IP is given the same IP address every time it connects to the internet. This is useful for servers that maintain a permanent presence on the internet. A static IP can be added to all John Lewis Broadband accounts.


An alternative way to download that allows you to view or hear the contents of a file as it arrives at your computer, rather than waiting for the full transfer to complete.


The common name given to the practice of viewing web pages on a computer.

Sync (or synchronisation)

Term used to describe the signal between your modem/router and the telephone exchange, if your hardware is 'in sync' then its picking up an ADSL signal.

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Test Socket

The test socket can be found behind the frontplate of any NTE-5 fitted master socket. Connecting to the test socket removes the possibility of internal wiring problems or other equipment causing problems with broadband and telephone services.


A thread is a series of messages in a newsgroup or forum that all relate to one particular topic. A newsgroup or forum will generally contain many different threads simultaneously.

TR-069 (Technical Report 069)

A protocol that defines a common method of communication between a router and an ACS server.

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The opposite of download - an upload takes place when you send a file from your own computer to another computer on the internet.

URL (Uniform Resource Locator)

The technical name for the address of a web page on the world wide web .

USB (Universal Serial Bus)

In a bid to cut down on the number of different sockets and ports on the back of computers, USB was introduced to allow connections to a computer through the same standardised socket type. Today it's used with a huge range of devices from mice to digital cameras.


Usenet is the collective name for a world-wide collection of newsgroups classified by subject.

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A virus is a computer program designed to replicate itself and spread between as many computers as possible. Sometimes a virus is harmless but they are often designed to damage your computer by destroying files or damaging your hard drive. Sometimes viruses are transmitted via email attachments, but they can also be hidden on floppy disks and CD-ROMs, so it's a good idea to use an anti-virus program to scan your emails and any disks that you may insert into your computer.

VoIP (Voice over Internet Protocol)

Allows you to make phone calls over your Broadband connection.

VPN (Virtual Private Network)

A secure, encrypted connection between two points over the internet. Often used by Home workers to access work systems.

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Web Browser

Software that allows you to view web pages. You're using a web browser to view this glossary page right now! The browser software available to you will depend on which operating system you use. The four most common browsers are Internet Explorer, Firefox, Chrome and Safari.


Small camera designed for the specific purpose of transmitting images over the internet.


Software designed to allow access to email via a web browser, as opposed to through an email client, such as Microsoft Outlook or Mozilla Thunderbird. Webmail for our customers is available via


Area of a web server used to store and display a website.

WEP (Wired Equivalent Privacy)

A security system used to protect wireless networks from unauthorised access. Due to flaws in the WEP protocol it's possible to break into a WEP protected network within a few minutes. We'd recommend using WPA if your wireless hardware supports it.

Wholesale Line Rental (WLR)

A service sold by BT Openreach, allows communications providers to offer their own telephone services over the BT Network. We use WLR to provide our Home Phone services.

Wi-fi (Wireless-fidelity)

Commonly used to signify the 802.11 standard - a form of wireless networking. Wi-fi connects a network without the need for physical cabling. Currently the most common forms of Wi-fi are 802.11b (capable of up to 11 Mbs) and 802.11g (capable of up to 54 Mbs). 802.11n is the latest wireless standard, offering transfer rates up to 300Mpbs, though many routers are N-lite, which offers transfer rates of 150Mbps.


The use of radio signals to connect computers without cables.

WPA (Wi-fi Protected Access)

A security system used to protect wireless networks from unauthorised access. The successor to WEP, created in response to serious weaknesses found in the previous system. WPA is considered to be as strong as the password that you protect it with.

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XML (eXtensible Mark-up Language)

A standard for creating mark-up languages which describe the structure of data.

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YouTube is a video sharing website where users can upload, view and share video clips.

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Zone File

A file stored on our DNS servers, contains information used by other servers to find out where to send requests for your website and email.

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Service Status

For full details of our current issues or any maintenance work that could be affecting your service please visit our Service Status site.

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