Sections of a disassembled x86 elf executable and when and in which order they are run

Question

I'm learning currently x86 assembly and trying some reverse engineering on a regular x86 elf executable. Now there are multiple sections like init main etc. I did a bit google research but didn't find quit what I wanted. Maybe somebody here knows where to read about this topic, as I really want to understand which sections get executed and the order of execution. I appreciate any links to this topic with detailed information.