Disabling default namespaces

Question

Rust seems to use some namespaces by default. For example, I don't have to use std::string::String and can simply type String. How can I define my own struct String without clashing with std::string::String? And where can I find a list of the namespaces that are included by default?

Answer 1

It's not a matter of 'default namespaces', it's the prelude.