What is `reactions`?

[h4x0rb0y]

I have looked at some posts requiring me to have some reactions. How can a user gain it? I don't find any written text here.

 

[Pernat1y]

Answer questions, post useful stuff and funny memes.
Basically, it is likes/dislikes.

 

[meeck]

here you go, I just liked ur post and now you got 1 reaction