[steveklabnik]

"unwrap" doesn't mean "panic". It means "to take out of some kind of container". So, the question is, what to do if the thing isn't in the container?

    unwrap: panic
    unwrap_or: produce this value instead
    unwrap_or_else: produce a value by running this closure instead
    unwrap_or_default: produce a default value instead

or and or_else are just like unwrap_or and unwrap_or_else, but they don't do the unwrapping; you keep the container.

In this case, the "container" is option, but similar types have the same methods, like Result.

> Why couldn't it just be .or() or perhaps .default()?

or returns Option<T>, unwrap_or returns T. .default returns the default value for a T already.

TL;DR: you have a lot of options (pun intended, sorry!) with what to do, but the names all follow a quite regular scheme.