Universal Apps are apps which work across multiple device types, such as desktop PCs, phones, tablets and the web. Developers can use a common code base across different versions of their universal apps for each major platform (such as iOS/Android) using a technique called "compiled code sharing." This allows developers to make changes once to the compiled source code and those changes will be reflected in all versions of that application.
Articles related to Universal Apps may be how-to guides for optimizing an interface for multiple platforms or descriptions of design patterns used in implementing universal interfaces. Related topics include cross-platform development, responsive design, and app store optimization.