PvP is shorthand for "Player vs. Player". Some online RPGs do not allow player vs. player combat at all; instead characters fight with NPC monsters. Camelot will be team-based PvP (based on Realm), where characters will be able to rise up to medium level without having to worry about being marauded by high-level enemies. As the players grow in stature, they will be expected to protect their realm from enemy incursions, as well as occasionally go on raiding parties against other Realms.
In order to allow new players some time to gain experience in the game, each Realm will have its own unique protected adventuring areas that are designed for new players. These areas will allow the new player an opportunity to gain experience without worrying at all about an invasion from across the seas.
Player levels will be based on experience vs. monsters, not vs. other players. At higher levels, players may adventure out into regions between the realms, which could bring them into conflict with enemies, but not necessarily so. The true PvP comes into play when actively going out on raids, or protecting your Relics from enemy invasions.
Each player accumulates "Realm Points" while either defending their Realm against enemy invasions or going out on raiding parties. As the player gains Realm Points, they can purchase special skills. For example, a player will be able to purchase abilities that increase their melee or casting damage, make them tougher or stronger, or negate some of the damage done to them. Additionally, at Realm Rank 5 all players gain a unique realm ability that no one outside their class can obtain. The game will not force players into PvP, but if you choose to do so, you will become more powerful.