Chains quests are quests that are tied together in sequence one after another. In the quests in scene editor you are able to connect your quests in chains through completion or failure to complete quests

Not only are you able to chain quests together one after another, you are able to unlock several quests by completing one quest or unlocking one quest after several quests have been completed. In this case you can even choose to have your players choose one quest over another for more information on this way of structuring your quests, see the levels and thresholds explanation here:

For example materials, see the Custom Quest Demo

If chaining quests together is not your thing or you have several minor tasks you want the player to complete in the same quest (this can help reduce clutter and make sure the quests that work towards the same goal all are named the same)