Book excerpt: Microdisplays are displays requiring optical magnification and OLEDs (Organic Light-Emitting Diode) are self-emitting displays where each pixel includes a LED made of organic material, in general composed of small-molecule organic material. This title reviews in detail how OLED microdisplays are made as well as how they are used. All aspects from theory to application will be addressed: basic principles, display design, display fabrication, operation and performances, present and future applications. The book will be useful to anyone interested in this rapidly developing field, such as students or researchers, industry professionals (engineers, project leaders) in the field of display development/fabrication and display end-users.