MTT Reduction refers to the process of reducing the complexity of a problem in computational theory, specifically in the context of complexity classes. It involves transforming one problem into another in such a way that a solution to the second problem can be used to solve the first. This technique is often used to demonstrate that certain problems are at least as hard as others. In computer science, MTT Reduction is crucial for classifying problems based on their difficulty. It helps researchers understand the relationships between different problems, particularly in the study of NP-completeness. By establishing these connections, MTT Reduction aids in identifying which problems can be efficiently solved and which cannot.