To be or not to be a senior

In modern development there is such a subjective concept as senior. One thing can be said about him for sure - he is expensive on the market. But who is he really? What can he do?

One often gets the impression that this is a character with superpowers, whose level is almost impossible to reach. Most likely, this is not the case. And despite all the subjectivity of such a notion, specialists of this level surely have a certain set of characteristics that help determine exactly what this engineer is.

In this discussion let's try to find this very "set" and figure out how to become a senior, what exactly he does, what mistakes he makes, what skills he has and how to develop as such a specialist. And all this on the example of software engineers in Android applications.