You can follow #tags too, although that has some limitations (for instance they don't show up in your home timeline but on separate pages). That's why the main pattern in !gnusocial (at least so far) is to follow groups or people instead.
@antranigv yes - if you want to "post to groups" or notify about your post in a group you use the ! sign. e.g. !gnusocial - if you are a member of this group it will highlight and members of the group will see your post. #hastags works like other #some tools. You can search for them.
@aroque Based on guessing, not knowledge: I think #hashtags are local to the posting instance, i.e. you might receive posts with that hashtag, _that have been created on your instance_. But not posts with that hashtag that have been created on other instances.. If you look at the link to #hashtag in this post, it points to posts with that tag on the Vinilox instance. Vinilox doesn't know that you have subbed to that tag on your instance, so the posts w…