A new feature has just been added to all trackers: bug voting. Voting is a way for users to express their interest in a bug who may not have anything new to add to the comments. How you use voting is up to you. Perhaps you’ll tell your users to vote for the bugs that they think are the most important to be fixed. Bug lists can then be sorted by the number of votes.
Voting is optional. You can enable it by ticking the “Allow voting on bugs” checkbox in your tracker’s settings.