Portal fantasy is a subgenre of fantasy literature where characters travel from the real world to a magical or fantastical realm through a portal. This portal can take many forms, such as a door, a wardrobe, or even a book. The journey often leads to adventures that challenge the characters and allow them to grow. Common examples of portal fantasy include works like C.S. Lewis's "The Chronicles of Narnia" and Lewis Carroll's "Alice's Adventures in Wonderland." These stories often explore themes of discovery, identity, and the contrast between ordinary life and extraordinary experiences.