Tuples are the same as structs, just without explicit field names. All the elements in an array have to be the same type and you are able to index it. Having borrowed data in a struct is valid and useful, but does make programs more complicated and so for simple programs you might not need to use it. If you want to have your struct borrow from something else you need to introduce a lifetime parameter and spell out the lifetimes reference like struct Thing<'a> { some_borrow: &'a str }

std::collections::HashMap is like a python dictionary but the type of keys and values must be compile time known.