Human interface guidelines (HIG) are software development documents which offer application developers a set of recommendations. Their aim is to improve the experience for the users by making application interfaces more intuitive, learnable, and consistent. Most guides limit themselves to defining a common look and feel for applications in a particular desktop environment. The guides enumerate specific policies. Policies are sometimes based on studies of human-computer interaction (so called usability studies), but most are based on arbitrary conventions chosen by the platform developers.