Mozilla has released a new feature in Firefox called tab groups, which allows users to organize their tabs into groups and label them. The feature was the most requested idea on Mozilla Connect, with over 4,500 people asking for it. The development of tab groups was a collaborative effort between the Firefox team and the community, with the team gathering feedback and iterating on the feature. The feature is designed to help users stay organized and focused, especially those who have a large number of tabs open at the same time.