Mastodon has two similar but significantly different features: Favourites and Bookmarks.
⭐ Favourites are the Mastodon equivalent of Likes, used to show appreciation. Click on the star below a post to favourite it. The author of the post is notified when you favourite it.
🔖 Bookmarks are for when you want to save a post and go back to it later. Click on the bookmark icon below a post (or in the ⋯ menu). Bookmarks are totally private, no one is notified.
@FediTips@the_turtle
So this is the big trouble with Mastodon - that there is a limit of characters ... here i am trying #sharkey a fork of #misskey and there is a higher character limit ;-)