This is an automated program that when put into a market scenario (trading strategy, MTS, see) allows for trade without a trader. The simplest advisors are built of the principle of “if... then...”. For example, if the price goes up by 20 points, then buy, if it goes down to 25 - sell, etc. Many advisors are available to download for free on the Internet and the vast majority of them are easily installed onto the terminal MetaTrader 4.0 (see). You can see the "Advisors" button on the top panel over the price chart window. Find out more about trading with advisors in the book “Mechanical trading systems: pairing trading philosopy with technical analysis” by Richard Weissman.