The FTSE 100 futures is

Information from: http://www.liffe.com/liffeinvestor/introduction/how/products/ftse100futs/what.htm

What is the FTSE 100 Index?
The Financial Times Stock Exchange (FTSE) 100 Index was launched in 1984. It tracks the share price movements of the top 100 companies. It is calculated every 15 seconds throughout the day from 08.00 to the 16.30 closing auction.

What are FTSE 100 Index Futures?
Broadly speaking, a futures contract is an agreement (obligation) to buy or sell a given quantity of a particular asset (e.g. shares, coffee, oil, government bonds, etc.), or an index based on such assets, at a specified future date, at a pre-agreed price. Depending on its terms, a futures contract will be settled either by delivery of the underlying asset or by payment of a cash sum that represents the value of that asset or index. Rather than requiring physical delivery of the underlying basket of 100 shares, LIFFE FTSE 100 Index Futures are cash settled.

The underlying instrument of the FTSE 100 Index Futures contract is the Financial Times - Stock Exchange (FTSE) 100 Index.

The FTSE 100 has long been a barometer by which professional money managers and private investors measure portfolio performance and is based on the share prices of 100 of the largest UK blue-chip companies.

You can buy the future ('go long') if you expect the market to rise, or sell the future ('go short') if you expect the market to fall. If your view is accurate and the market moves your way, every index point move earns you £10, if it moves against you, it costs you £10.

For example

Every FTSE 100 Index Futures contract has a value. To determine the contract's value you need to know the value assigned to each index point and the current index level. Multiply the level of the index (e.g. 6000) by the index point value (£10), and you will arrive at the 'value' of the contract, in this case £60,000. If you buy one FTSE 100 Index Future you are trading an instrument with an underlying value of £60,000.