Parameter

In mathematics: A parameter is like a variable, but it's more built into the function or relationship.

It sets a specific value for that particular function or relationship.

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

h(year) = 20 × year
(This "20" tells us this tree grows 20 cm per 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

Sometimes, we also use a parameter (like 't' for time or 'θ' for an angle) as a variable that helps us draw a curve.

Example: To draw a circle, we might use:
• x = 5 cos(t)
• y = 5 sin(t)
As 't' changes, it traces out the points on the circle. Here, 't' is the parameter helping us draw the curve.

 
In software: A parameter is the name given to any value that is 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. (The argument is the actual value supplied to the parameter.)