Shadowlands has introduced "perks" to the skills system. Can you elaborate on their mechanism?

The perks can be explained as benefits, or extra powers which you can train. There are hundreds of them, 852 in fact, and they come in three categories; profession, general and team. The professions ones are tied to, you guess it, your profession. It means lots of new abilities and attacks, just for your profession. Team perks are powerful attacks which can be unleashed when several players work together. It’s a new take on “social” combat gameplay :-)