Literacy is the ability to read and write. The inability to do so is called illiteracy or analphabetism. Visual literacy also includes the ability to understand visual forms of communication such as body language, pictures, maps, and video. Evolving definitions of literacy often include all the symbol systems relevant to a particular community. Literacy encompasses a complex set of abilities to understand and use the dominant symbol systems of a culture for personal and community development. In a technological society, the concept of literacy is expanding to include the media and electronic text, in addition to alphabetic and number systems. These abilities vary in different social and cultural contexts according to need, demand and education.