An expert advisor is a piece of software which works as a plug-in for your trading platform. The purpose of an expert advisor is to automate your own (or someone elses) trading system.
An expert advisor works by monitoring any market for you 24 hours a day, looking to place trades for you once it sees that certain parameters (based on your own, or someone else trading strategy) have been met.
To build your own expert advisor, you need to have a working knowledge of the MetaQuotes Language 4 (MQL4) which is the built-in language for programming trading strategies. There are companies which will (for a fee) automate your trading strategy and build an expert advisor for you based on your own settings. There are also companies which will sell you their own expert advisors.
Most forex expert advisors are developed for the Metatrader trading platform. Developed by Russian programmers, Metatrader had become the standard trading platform for many professional traders and forex brokers.
Once you have built your own expert advisor (usually a file ending in .EX4) or purchased someone elses, the process of setting it up with Metatrader 4 is quite simple. It...