When you make a new post to ask a question or to ask for any advice, you can mark someone's answer/comment as the 'Best Answer'.
To do this, all you have to do is click/tap the 3 little dots in the top right corner of a comment and then select 'Mark as Best Answer'.
This will move that comment to the top of the comments section permanently and allow others to see the most useful answer to topic.
You can also see how many 'Best Answers' a member has by visiting any profile.