The main options for access from home are:

• Standard Dialup
• ISDN
• Broadband - cable
• Broadband - ADSL

Most people use this at home although it is gradually being replaced in popularity by broadband. You dial in to your Internet Service Provider service using a standard analogue modem attached to your computer and your normal phone line. Data is sent at a maximum speed of 56Kbps (kilobits per second).
This is slower than other methods because its using an analogue service. Some services use a "local" number and charge per minute; others charge a flat rate.

Integrated Services Digital Network uses two or more digital phone lines. Like standard dialup a connection has to be made each time you want to access the Internet - however the connection is made faster than for standard dialup. Data is also sent more quickly at 64Kbps or 128Kbps. ISDN is now available nationwide. You need a USB port on your computer or, on older computer an ISDN Terminal Adaptor/ISDN Card.

ISDN appeared before broadband but is now becoming less popular.

Cable broadband uses a high-speed cable modem and fibre-optic cable rather than a standard phone line so this frees up your phone. The company provides the necessary software and a special cable modem (usually in a set top box) which connect into a USB port on your computer. Cable broadband is not yet available everywhere - see suppliers' web site to find out if it is available in your area. You may also have the option of buying cable digital TV and telephone services. Data transfer speed depends on the level of service you purchase but can be up to 1Mbps - 20 times faster than a standard dialup. You are always connected and usually pay a flat rate monthly fee. There may be a one off connection fee.

For more about cable broadband see http://www.howstuffworks.com/cable-modem.htm

Asymmetric Digital Subscriber Line uses a special telephone modem (supplied) that cconnects between a USB socket on your computer and your telephone line. It runs into a high-speed digital line capable of carrying data up to 10 times faster than a conventional dial-up connection. You need to be in range of the service (see providers' web sites). Connection is established each time you switch on your computer. Typically Internet access is charged at a flat monthly rate, whilst phone calls are charged per minute.
Maximum speeds are around 512Kbps .

All ADSL lines, regardless of service provider - are subject to contention, meaning that the network bandwidth available is shared between a number of subscribers. The ratio to which the available bandwidth is shared between users is called the "contention ratio". All UK providers, including BT, are subject to the same contention ratios.