Euclidean norm

The Euclidean Norm is a way to measure the size of a particular thing, whether it is a number, a vector or a matrix. To imagine it in a simpler way, it is like if you wanted to measure the size of an object in the real world, like a ball.
First, you would have to measure each of the three dimensions of the ball: height, width and depth. Then, you would take the numbers for each of these dimensions and add them together. This would give you a total size for the ball. The Euclidean Norm does the same thing, but instead of measuring a ball, it is measuring a number, vector, or matrix.
It looks at each piece of the number, vector, or matrix separately and adds them together. The Euclidean Norm is usually written as the square root of the sum of the squares of all the pieces. That just means that you add up the result of each piece taken to the power of two. This gives you the size of the number, vector, or matrix.