Imagine you have toys and you want to play with them in different ways. You can put them in a different order, or turn them around, or flip them over. These are all different ways of changing the way you play with them. In math, we also have ways of changing how we look at things, called transformations.
A unitary transformation is a special type of transformation that preserves certain qualities of the numbers or vectors we are working with. It's like playing with your toys, but making sure that they stay the same colors and shapes they were before.
When we do a unitary transformation on a vector or matrix, we use a special type of matrix called a unitary matrix. This matrix has some special rules that let it keep the same shape and size as the original vector or matrix. It also keeps some special qualities of the numbers or vectors, like their lengths or angles, which is like making sure your toys keep their shapes and colors.
Unitary transformations are important in math because they help us understand different ways of looking at the same problem. Just like you can play with your toys in different ways, we can use unitary transformations to see our numbers or vectors in new ways that might be easier to work with.