A function can be called from another function.

When the Python interpreter encounters a function definition, it "remembers" the name of the function, the number of parameters, and does not go through through the function body.

Variables created inside a function body are stored in the same location in memory as other variables.

Local variables are shared between functions.

The "best" way to access data from a function is to pass in the data via arguments $($parameters$).$

The function header is the first line of the function definition and begins with the keyword def.

A function must be defined before it is called.

Functions can return a single value$($s$).$