Complex sentence: In mathematics, K-theory is an extraordinary cohomology theory which consists of topological K-theory and algebraic K-theory and spans the subjects of algebraic topology, abstract algebra and some areas of application like operator algebras and algebraic geometry.
Split into simpler sentences: In mathematics, K-theory is, firstly, an extraordinary cohomology theory which consists of topological K-theory. It spans the subjects of algebraic topology, abstract algebra and some areas of application like operator algebras and algebraic geometry.