All levels grouped into episodes (or chapters). Each episode has a different story, mascot, and name (except, Minty Meadow, Soda Swamp, and Candy Clouds, there are two different episodes with same name). The episode name has 1, 2, or 3 words. Most episodes have the same initial consonant sounds. There are currently total of 139 episodes (6 episodes in the first ten worlds, 3 episodes each in World Eleven onwards in Reality and 45 episodes in Dreamworld (seven worlds: 6 episodes in each except World Eight). Dreamworld has now been released in its entirety so no more Dreamworld episodes will be released but there will still be more episodes in Reality.
The first two episodes contain 10 levels, the rest contain 15. At the end of each episode (starting with Candy Factory on web, or Lemonade Lake on iOS and Android), to cross over to the next episode, you have to get three of your Facebook friends to give you a ticket to cross, or buy 9 gold bars (3 gold bar for each ticket). On Android or iOS, you can complete mystery quests (including three daily quests) to cross to the next episode if not synced with a Facebook account. Each episode has its own mascot and special logo, too. The mascot is usually a person or an animal, or other things such as a robot, a vampire, and even a fairy. The logo is usually the episode's name in bolded words with a background striped banner to match the episode's area. Usually each mascot has a problem and Tiffi solves it for them and they turn happy (most of the time). After dreamworld ended, she hasn't really helped with problems since there aren't any right now.
On November 27, 2013, Dreamworld was released, with whole new episodes and levels. Each episode imitates an episode in Reality, but usually in a slightly difficult manner. There are some exceptions though, e.g. Dreamworld level 30. To get to Dreamworld, you have to click on an owl named Odus on the map screen. Click on Odus again to return to Reality.
Here are all the current episodes in Candy Crush Saga, divided into worlds: