Going through the Rust Book

Parts of memory available to you code to use at runtime.

Stack

• last in, first out
• push, pop
• All data stored here must have a known fixed size.

Heap

• you request a certain amount of data
• the memory allocator finds an big enough empty spot
• returns a pointer
• called "allocating on the heap"

Adding and accessing data in the stack is faster than the heap.

• Each value inRust has an owner.
• There can only be one owner at a time.
• When the owner goes out of scope, the value will be dropped.

Heap data is moved. Stack-only data is copied.

A reference is like a pointer, but is guaranteed to point to a valid value of a particular type for the lifetime of that reference. The action of creating a reference is called borrowing. You cannot modify something you are borrowing.

Use &mut for a mutable reference.

If you have a mutable reference to a value, you can have no other reference to that value.

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