Twitter hasn’t specifically built functionality for these use cases, but they do offer the ability to star a tweet. What is starring even for? Twitter doesn’t specify how or why you might want to star something, and indeed there are at least 5, if not more, ways that people have decided to use this functionality. But, that’s the point—it’s precisely this kind of simplicity and ambiguity that allows people to use starring in the way that is useful for them personally.
It’s an interesting concept for product designers: to move from linear use cases that achieve a user story to generalized “sandboxes” and features that can solve different problems for different people. Twitter’s starred tweets feature is perfect example.