To understand why we use `numbers`

as we do, you must first understand why we use parameters.

As of defining the function, the program does not know whether `numbers`

is a number, a string, a list, a dictionary, etc. As far as the program is concerned, `numbers`

could be anything, and the the program could care less. It's just a placeholder for whatever you pass into the function when you actually call it. In other words think of parameters like variables, whenever you call a function, the argument you pass into it becomes the value for `numbers`

. For instance if you called:

`total(n)`

You would essentially be telling the program to run `total(numbers)`

except now, `numbers = n`

. Until a function is actually called, the parameters you have set are valueless placeholders. Once you call the function and pass in arguments for those parameters, they take on value and purpose. What I mean by this is, if you did the following:

```
n = [3, 5 7]
def total(numbers):
result = 0
for x in range(len(numbers)):
result += numbers[x]
return result
total(n)
```

Notice how I defined the function using `numbers`

as a parameter and then I called the function using `n`

as an argument. This is telling the program to run the code within `total(numbers)`

but replace all mentions of `numbers`

with `n`

. Basically, it does this:

```
result = 0
for x in range(len(n)):
result += n[x]
return result
```

`n[x]`

is an identifier for the value of `x`

in the list called `n`

.

Without specifying a list and using `x`

as an identifier, the program would just add the numbers 1, 2, and 3 to `result`

since that is the length of `n`

. That is not what we want.

This is why we use `numbers`

as we do in the function.