There is a recommendation algorithm in the newest versions; your instance has an explore tab that shows popular hashtags, posts and accounts, plus popular articles shared in many tweets. The instance admin has to greenlight them on a case-by-case basis (though you can greenlight an entire website if you want and it amounts to 10 minutes of work a day).
The algorithm is entirely based on "how many users did use this hashtag/share the post/share the URL/interact with account in the past week".
The algorithm is entirely based on "how many users did use this hashtag/share the post/share the URL/interact with account in the past week".