FIX is a simple protocol, typically consisting of key-value pairs in its most common form. However, that's not the entire picture. The protocol involves a lot of complex logic, including validations and rules. Although it was developed in the 1990s, it remains widely used today.

Basically, the process involves connecting and handshaking through a series of messages, which results in an active FIX session. Once the session is established, you can send bidirectional messages, such as requesting a market data snapshot to receive prices, submitting a new order, or anything in between.