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