One use case is the idea of the Collection Pipeline discussed by Martin Fowler on his blog (https://martinfowler.com/articles/collection-pipeline):
"Collection pipelines are a programming pattern where you organize some computation as a sequence of operations which compose by taking a collection as output of one operation and feeding it into the next."
We can use an Observable to do operations such as map and reduce or groupby on sequences of objects when processing data.
Observables can be created for diverse functions such as button events, requests, and RSS or Twitter feeds.
