max()
-- Find highest value

Syntax : mixed max ( number arg1, number arg2 [, number ...])mixed max ( array numbers [, array ...])
max() returns the numerically highest of the parameter values.
If the first and only parameter is an array, max() returns the highest value in that array. If the first parameter is an integer, string or float, you need at least two parameters and max() returns the biggest of these values. You can compare an unlimited number of values.
Note: PHP will evaluate a non-numeric string as 0, but still return the string if it's seen as the numerically highest value. If multiple arguments evaluate to 0, max() will use the first one it sees (the leftmost value).