Parameter

In mathematics: a value that is more "built in" to a function. It is similar to a variable, but stays fixed while we use the function.

Example: in this function for the height of a tree the "20" is a parameter:

h(year) = 20 × year

We can change the parameter!

Example: A different tree's growth rate is 30 cm per year, so its function is h(year) = 30 × year

We could even make it more general by writing

h(age, rate) = rate × age

In software: it is the name given to the values that are passed in to a function.

Example: in this function, "val" is a parameter:

function double(val) {
return val*2
}

When we call the function such as double(7), then "7" is called an argument.