Quests (or tasks) help your progress in the game and to level up your buildings/characters.

There are 2 different quests, single quests and couple quests.

Single quests allow you to gather XP+coins and to unlock new buildings or new characters.

Couple quests (the quests where you can assign multiple characters) allow you to upgrade your relationship status and unlock sex scenes/images.

On the right side of the screen, you can see the characters and what quests are available for each one for them.

When a character image has a red background with a play icon at the top, it means that there are new quests available for that character. A blue background with a timer icon shows that the character has quests in progress, and if there is a check mark on a blue background, it means that the character has finished a quest.

Character traits are also important when you take on new quests. Some quests improve some of your character traits. By selecting the correct characters for a specific quest this will enable you to complete the quest faster.