Kanka is an online worldbuilding and table top RPG campaign management website. Its goal is to help people organise the worlds they play in or are writing. This can be for a group of friends playing Dungeons & Dragons, or someone writing a book and needing to have a place to keep track of the people and locations of their setting.
Kanka has a similar approach to wikipedia or OneNote. You can create and describe your worlds, but with the added benefit of offering a more standard structure, and integration between the various elements.
On the most basic level, a world, or campaign as they are called in Kanka, is comprised of characters and locations. There are over fifteen different types of entity types, and each year more get added.