Experience
From Guild Wars 2 Wiki
Experience 
(also exp and XP) is rewarded for performing and completing different objectives in game. As you gain in experience you gain levels, increasing your basic abilities.
[edit] Gaining experience
Experience is awarded for doing different things in game:[1]
- Participating in events. Experience is awarded to each player based on how much they participate in an event.
- Killing creatures. Full experience is awarded for each player involved. In general, participation is defined as being responsible for at least 5-10% of damage dealt to an enemy.[2]
- Completing personal storyline steps.
- Completing renown hearts.
- Participating in dungeons.
- Reviving a player.
- Discovering new points of interest.
- Completing daily achievements.
