Chemistry of bimetallic systems is currently the topic of interest in surface and catalytic science. A number of interesting phenomena such as segregation, faceting, reconstruction and chemical oscillations, which have direct correlation with the atomic scale modifications of these surfaces are emerging in this field. Bimetal single crystals and bimetallic overlayers fabricated on metal substrates are being used to investigate the properties of bimetal surfaces by employing surface spectroscopic techniques such as AES, XPS, LEED, LEIS, and STM. Some of these studies are concerned with the heteronuclear metal-metal bond present in the top surface layers. The surface structures impart unusual chemical and catalytic properties to bimetallic systems. This article reviews the current understanding of the topic, highlighting the preparation methods of mono and multilayer binary alloy surface phases, and various investigations on physical and chemical phenomenon occurring on them. It also touches upon the chemisorption and catalytic properties of these fascinating bimetal surfaces.