Your log book is (or should be) simply for your own enjoyment. Resorts or instructors may occasionally ask to see a copy -- although this seems kind of dopey because many of us use online or electronic log books, and log entries can be forged. It isn't a legal document.
In my log book I have to fill out a nice reasonable level of dive detail. It's a great recap to provide future recollection of events. I like this a lot. However at the bottom of the page there is a place for the dive professional to sign off.
If I dive with a buddy there is no dive professional with us. Curious if that dive cannot be registered without a dive professional. Is that somehow an optional verification of some sort?