Twitter’s feature for privately organizing saved posts is called Bookmarks.
Bookmarks let users save posts for later without publicly liking or retweeting them. Twitter introduced the feature in 2018, giving people a private way to keep recipes, articles, threads, references, and other posts they wanted to revisit.
The feature addressed a limitation of the Like button: likes could be visible to others and were not designed primarily as a personal filing system. Bookmarks created a separate private collection accessible from the user’s account menu.
Bookmarks are different from Lists, which organize posts from selected accounts into a timeline, and different from browser bookmarks, which save web pages locally or through a browser account. On X, the saved item is the post itself, subject to the post remaining available.