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In mathematics, the norm of a vector is its length.

A vector is a mathematical object that has a size, called the magnitude, and a direction.
For the real numbers, the only norm is the absolute value.
For spaces with more dimensions, the norm can be any function p with
the following three properties:[1]

1) Scales for real numbers a, that is, p(ax)=|a|p(x).
2) Function of sum is less than sum of functions, that is, p(x+y) <= p(x)+p(y)
(also known as the triangle inequality).
3) p(x)=0 if and only if x=0.

https://simple.wikipedia.org/wiki/Norm_(mathematics)