Hand shifting is something that happens a lot when you play bass guitar. It's a technique you definitely need to get down.
I recently filmed a lesson on it:
That lesson and this use examples from my book Complete Fingerstyle Bass Technique.
The thumb pivot allows you to play a larger span of frets than the 'standard' one-finger-per-fret system and means you don't have to shift your whole hand. Check out the video for a complete breakdown with a soul bass example.
The backing track and PDF are below the video.
Soul Bass Backing Track & Example
Complete Fingerstyle Bass Technique is available on PDF, Kindle, and Paperback.