What is Expert Advisor?

What it means

An EA is attached to a single chart and executes on each incoming tick or on each new bar. It has full access to price history, indicators and the account, and can place orders without human confirmation — which is what separates it from an indicator or a script.

Why it matters

Because it runs in the terminal, an EA stops when the terminal stops. Closing MetaTrader, losing internet, or a Windows update restarting the machine all halt trading, and any position already open stays open with no supervision. This is the operational risk that a VPS exists to address.

What this changes in practice

Several things must be true before an EA will trade at all: the algorithmic trading button must be enabled, the EA must be permitted to trade in its own properties, the chart must show a smiling face rather than a sad one, and the symbol must match. Each has its own failure mode — start at EA not taking trades.