Player versus Player

Player versus Player (PvP) refers to combat between players. On regular maps, PvP combat is disabled, so players cannot attack each other there.

To battle against other players, you have three options:

The Castle of Schwartzwald is always enabled for PvP. No experience will be given for player knockouts.
Once you reach Level 10 or higher, you can queue for battlegrounds. In some battlegrounds it's everyone for themselves, whereas in others you will fight in a team (against the other team). In battlegrounds, you receive small experience bonuses for defeating other players.
Finally, Guild versus Guild battles occur twice a week: once on Tuesday, and once on Saturday, at 6:20 ET after the Battle for Schwartzwald Castle.

While you in PvP, your armor will not take any damage if you get knocked out.
Battleground rewards are participation based. You will receive tokens even if you lose, as long as you tried. Likewise, if someone does not participate, it can well happen that even if they win, they receive fewer tokens than someone who lost, but participated.