How Does Apex Work in Salesforce

Question

How Does Apex Work?

Answer 1

All Apex programs runs entirely On-Demand on Force.com Platform.

First the platform application server compiles the code into abstract set of instructions that can be understood by Apex runtime interpreter.

The compiled code is stored to metadata.

When the end users triggers the execution of Apex by clicking button or VisualForce page the application servers retrieves the compiled instructions from the metadata and send them to runtime interpreter before returning the result.