Operator theory

Operator theory is the study of how certain mathematical functions perform with the things they act on. Basically, it's a way of studying how certain functions affect different mathematical objects. For example, if you have a function that adds two numbers together, like 3 + 5, this is an operator. Operator theory looks at how that operator works on different types of numbers, like decimals or fractions. It also looks at how it works when the same operator is used twice in a row, like (3 + 5) + 2.