What does the 'sample' filter do in simple queries?

Newb here learning simple queries, but I can’t find any info on this:

selecting it shows value 1 - 100

Afaik, it’s the number of results to display (x random samples matching the query parameters).

Tx! You’re right. I just tried it.
I can’t think of a use case, though.
Where would one use this?

A query that returns a lot of results will take a lot of time to complete and will consume a lot of memory.
By getting a sample, you make sure that the query at least returns what you are actually after, before getting all of the desired results.