## Definition

When you take a look at mathematical formulas most of them usually have alphabets say **x** or **y** in them, and the intention is that anyone using these formulas will replace the **x** and **y**s with actual values. In the programming world functions can be viewed as these formulas and parameters will be the **x** and **y**s.

## Use Cases and Examples

Here is an example of a function in Javascript that adds two parameters together:

```
// declaring the function
function adder(a, b) {
return a+b;
}
// using the function
adder(1,2);
```

What you have above is a function called **adder** that takes two parameters and returns the sum of `a`

and `b`

. The last bit of the code shows how you will use this function.
You will refer to the values you pass in to replace the parameters as arguments.

## Summary

Parameters are key to how we end up getting different behaviors out of the same piece of code.

All terms