Agricultural extension was once known as the application of scientific research and new knowledge to agricultural practices through farmer education.

However, extension has various meanings to different extension professionals involved in promotion of new ideas and information and building capacity among various groups of people – not just farmers. See extension agency. An extension agency is an organisation that practises extension, in the context of community development. ...

Historically the term extension is said to have arisen from university programs designed to extend new knowledge to British city populations. It was adopted by agricultural, health and other agencies in the Americas and other regions, where extension services are often a major feature of rural life.

Extension practioners today work in a number of extension domains, and are represented by several professional organizations (such as APEN), networks (such as AGREN) and extension journals (such as Journal of Extension).

An extension agent is a university employee who develops and delivers educational programs to assist people in economic and community development, leadership, youth development, family issues, agriculture and environment. Another program area extension agents provide is 4-H and Youth. Many extension agents work for cooperative extension service programs at land-grant universities. They are sometimes referred to as county agents or educators. 4-H is a youth organization administered by the United States Department of Agriculture Cooperative Extension System with the mission of empowering youth to reach their full potential, working and learning in partnership with caring adults. 4-H now serves over 9 million members from ages 8 to 19 in... The cooperative extension service, also known as the Extension Service of the USDA, is a non-formal educational program implemented in the United States that is designed to help people use research-based knowledge to improve their lives. ... Land-grant universities (also called land-grant colleges or land grant institutions) are institutions of higher education in the United States which have been designated by Congress to receive the benefits of the Morrill Acts of 1862 and 1890. ... Originally, in continental Europe, a county was the land under the jurisdiction of a count. ...