Linear stories
Linear
Linear stories are single chapter-by-chapter narratives.
This is a traditional story, the same kind you've probably read thousands of. We need a special word for it to distinguish it from Interactive stories.
Different authors can still collaborate on a linear story, but the structure is a single sequence of chapters rather than a branching tree, which makes a collaborative Linear story a Round Robin.
This is a story type tag. These tags describe the structure of a story and how you can add chapters, among other things.