The idea of a function is to assign a set of code, and possibly variables, known as parameters, to a single bit of text. You can think of it a lot like why you choose to write and save a program, rather than writing out the entire program every time you want to execute it.
To begin a function, the keyword 'def' is used to notify python of the impending function definition, which is what def stands for. From there, you type out the name you want to call your function. It is important to choose a unique name, and also one that wont conflict with any other functions you might be using. For example, you wouldn't want to go calling your function print.
def example(): print('this code will run') z = 3 + 9 print(z)
Here we've called our function example. After the name of the function, you specify any parameters of that function within the parenthesis parameters act as variables within the function, they are not necessary to create a function, so first let's just do this without any parameters.
Now if we just run this, we see nothing happens. We have to actually call this function to execute, because all we've done so far is just define the function and what it does. To run it, you can either type out the function in the console like so:
This is notably a very basic function. We can put all types of code into a function. We can put if statements in there, run other functions in them, all sorts of things. Also, we can begin to learn how to use function parameters and then later function parameter defaults.