Abstraction is the most fundamental idea in computer science, but it's hard to define until you've seen some examples. The most basic kind of abstraction is to give a name to something in a program. For example, here we gave the name who to the idea "pick an item at random from this list of people (or cats)." This is called procedural abstraction because we use a procedure (a block) to name the idea. This makes your code readable. You'll see other kinds of abstraction later.

A procedure is a named sequence of instructions that may take inputs and may report a value. Some languages call procedures methods or functions. Here are two types of procedures you have seen in Snap!

Reporters have an oval shape. They report a value.

Commands have a jigsaw puzzle shape. They tell the computer to do something without reporting a value.