4.1. What is Ownership?

The main purpose of ownership is to manage heap data.

4.2. References and Borrowing

• At any given time, you can have either one mutable reference or any number of immutable references.
• References must always be valid.

4.3. The Slice Type

• String literals are string slices of type &str .
• Defining a function to take a string slice instead of a reference to a String makes our API more general and useful without losing any functionality. We can pass a String to a function accepting &str thanks to deref coercions.