What are the interactions that give a user XP?

Question

Do you get XP for posting a code or following a person?

Answer 1

Challenges, earning badges, getting code of day and getting their answer marked as best

Answer 2

Challenges and Badges are the ways to gain XP. You don't get XP for posting a code. You will get XP if you unlock a related badge like 5/10/50 codes with 5+ upvotes etc,. The same applies for questions/answers too. And with the recent update, you can get 16 or so XP if your answer to a question is marked as best.