Media Library – Attach

I’ve been searching for an answer for well over a week now & can’t find any info on what attaching media to a post does. I expected to see a section on the post’s page with a list of attached media & its link or something.

In tutorials I’ve seen, they just upload the media, copy the direct link & paste it into a custom field in a post & grab that in the WordPress code, all without ‘attaching’ it to the post in the media library. So what benefit does attaching offer?

Btw, I’m new to CMSs if you hadn’t guessed ??

Thanks for any help