Abstract
In this contribution, we will review the concepts and principles used to characterize and discuss the structure, stability, adsorption properties and catalytic reactivity of bimetallic surfaces in an atomic scale picture. Starting from early stages, we will emphasize recent experimental and theoretical findings that resulted in a rapidly improving atomic-scale understanding of adsorption and catalytic surface reactions on these surfaces. While examples are often taken from our own work, the resulting insights are of general validity.