There are two ways of classifying the Hero's Journey; the original 17-step list proposed by Joseph Campbell in The Hero With a Thousand Faces, or the 12-step modern reinterpretation from The Writer's Journey by Christopher Vogler. Note that these steps do not always have to be sequential; in theory, any step can be used at any time. Also, the term hero refers to both male and female protagonists.
Ordinary World - This is the hero's environment prior to the events of the story.
1. The Call To Adventure - A hero is thrust into a situation that forces him/her to step out of his/her comfort zone(s). Can often be in the form of a messenger (i.e., Navi).
2. Refusal of the Call - The hero rejects his/her calling out of fear, doubt, laziness, etc. This will often lead to the hero getting thrust into a situation that makes going on the journey unavoidable.
3. Supernatural Aid - The hero is aided by a mentor, typically an older individual who has followed the heroic path already and is now assisting others. A common motif is that of the wise old hermit or sword master (i.e., Obi-Wan Kenobi). The hero is also given a gift, be it a weapon, ability or otherwise that he/she can use to accomplish his/her mission.
4. Crossing the First Threshold - Now that the hero has accepted the Call and has the assistance of a Supernatural Aid, he/she is ready to take the first step into the Special World. This is considered the "point-of-no-return" in most stories.
5. The Belly of the Whale - The hero is fully removed from the world that they once knew, and undergoes a symbolic "death" that leads into the next step.
Initiation - The hero leaves his old world behind and must learn to adapt to the Special World.
6. Road of Trials - The hero must undergo a series of tests and/or obstacles in order to complete their objective. Often this takes the form of boss stages in video games. In many cases, the hero faces "Threshold Guardians" whose characteristics he/she must incorporate into themselves (i.e., boss abilities in Mega Man).