**Paul Baum**

University of Penn State, USA

February 28, 2013

**What is K-Theory and what is it good for?**:
This talk consists of four points.
1. The basic definition of K-theory
2. A brief history of K-theory
3. Algebraic versus topological K-theory
4. The unity of K-theory
The talk is intended for non-specialists. Only a general mathematical
background will be assumed.