Why We Should Compile From Source

Hi guys. I am new and I want to know why some people are compiling engine from the source code? What is the difference between using default UE4 and the version compiled from source code? Also one guy said that "I am learning Engine API by compiling Engine from source code. Is it impossible to see source code without compiling Engine from source code?

Thank you!

The version in the launcher it the newest stable version, however since there’s months between releases you can test out new features before a big release by compiling the current source. Besides that, sometimes you can’t do something with Blueprints or you prefer to code something in and so the source is available for that. You don’t need to compile the source to take a look at the code though.