Quests are Tasks and Missions given from NPCs to Players. In return for finishing quests, you receive money, crate keys, special items and more. Quests can have multiple objectives and form quest lines with smaller quests inside.
By default, every player has access to dimensional quests. These quests are quest lines seperated into 5 steps, increasing objective amount and rewards for the same objectives. Upon unlocking a new dimension like the nether, nether dimensional quests get unlocked as well.
Example for a regular dimensional quest: Mine 64 stone, Mine 128 stone, Mine 256 stone etc.
Quests cannot get abandoned, and it is only possible to hold one quest at a time. Once a quest has been accepted, it has to get completed to accept a new one.
To view all of your active Quests, check out your quest board at /quests