X Product Lead and Solana Advisor Nikita Bier announced that X has officially launched one of its major updates: Custom Timelines. This feature allows users to pin specific topics to the top of the homepage tab bar, currently supporting over 75 topics. The system is powered by Grok, which combines deep understanding of each post with algorithmic recommendations to dynamically generate each timeline based on user interests, especially effective for topics with existing interaction preferences. Currently, Premium subscription users on iOS can access early, and the Android version will be launched soon.