clustering

 Clustering  is an approach to displaying similar or related items (such as sequential posts) as a summary or together in some other reduced form that takes less space, uses fewer words, than if the items were displayed separately.

Use cases
There are numerous uses for clustering, e.g.
 * composite stream - a composite stream can be made more readable and more easily skimmable by clustering adjacent similar items
 * notifications - a series of notifications can be displayed more compactly by clustering notifications about the same item, or from the same person, or both.

Specific Methods
Clustering methods may differ in different situations and for different types of items.
 * notifications: Clustering
 * like text display clustering
 * photo posts: Clustering