Quest giver
From Guild Wars Wiki
A Quest giver is an NPC who has a one or more tasks for you to complete. Some quests are required to finish the game (i.e. primary quests), while others are optional. Quests usually unlock skills, give you items (common and rare), give you experience points, and increase your reputation with certain factions.
It is advisable to do as many quests as you can, especially the ones that reward skills. Having many skills will help you build the team of heroes you want. Note that some quests are only available to certain professions. Some quests only give you experience and/or gold.
