Agricultural extension is 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.

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 organisations and extension journals.