This paper presents an overview of proximity wireless communication (PWC) technologies, their principles, design guidelines and practical applications. In particular, two different applications of PWC are reviewed. One is PWC between stacked chips. Both communication distance and coupler size are several tens of microns. Area and energy efficient design techniques are introduced. Another is PWC between module boards. Both communication distance and coupler size are several millimeters. Energy and area efficient practical designs are introduced for mobile and industrial machinery applications.