Twitter is globally rolling out a button for bookmarking tweets, the company said on Wednesday. Tweets that are bookmarked with the new tool will be kept private, presumably to provide users with more privacy around their interests instead of having to publicly explain why they've bookmarked a particular tweet.

Why it matters: This is part of an ongoing evolution of Twitter's product. For years, many used its somewhat-ambiguous, star-shaped "favorite" button to bookmark tweets, but the company's switch to a heart-shaped "like" button in 2015 has complicated the meaning.