there should be a function for following a thread, just like on facebook. Right now you need to post an aswer to get notifications, and you cant be expected to always be able to contribute something useful to a thread you want to follow. Or is there such a fuction but I dont know how to use it?
If you "star" a question, you'll get notifications of new answers.
FYI, we don't have "threads" here in the forum sense. Threads are ordered and have replies, but answers to questions can appear in any order, because the votes on the questions change. This means an answer can't reply to another answer. Comments are used for that instead, but remember (1) unlike Facebook comments, they're only temporary, and can be deleted without warning; (2) they don't contribute to search results, so you need to make sure all the useful information ends up in the questions and answers themselves.
There is (sorta).
Below each question's vote arrows you have a star
once you click it, you can visit your profile at this page:
and you will see highlighted in yellow each question you starred that got updates.