Side effects in Programming

A few years ago, I was showing code I’d written to a friend in order to get feedback and one of the things he pointed out to me was that a function I’d written had side effects. This was the first time I’d heard this term.
After the call with my friend, I googled around to try and understand what he had meant. I started with the Wikipedia page and followed that up with a few blog posts. Everything I read wasn’t…