Enemy Follow Player tutorial?

I’ve been looking for a tutorial to make an object follow the player for a while now, but I can’t seem to find anything. Does anyone know of one that I can use? (Preferably C#) I see many questions about this kind of script but I don’t want to copy and paste, you know?

Have a look at this :

There was a very nice tutorial before, but I can’t seem to access it, I get “Forbidden - 403” error.
https://unity3d.com/learn/tutorials/projects/stealth-tutorial-4x-only/stealth-project-overview

It also depends if you’re in an open world or rather encumbered environment, you may not need to use navigation.