A science fair is generally a competition where contestants present their science project results in the form of a report, display board, and models that they have created. Science fairs allow students in grade schools and high schools to compete in science and/or technology activities.

One of the main educational advantages of science fair is that it requires completing a larger project than can be easily included in the short periods provided in most schools. Although writing assignments that take a long time to complete and require multiple drafts are fairly common in US schools, large projects in the sciences (other than science fairs) are rare. Science fairs also provide a mechanism for students with intense interest in the sciences to be paired with mentors from nearby colleges and universities, so that they can get access to instruction and equipment that the local schools could not provide.

Science is, in its broadest sense, any systematic knowledge-base or prescriptive practice that is capable of resulting in a prediction or predictable type of outcome. In this sense, science may refer to a highly skilled technique or practice. In its more restricted contemporary sense, science is a system of acquiring knowledge based on scientific method, and to the organized body of knowledge gained through such research. Science is sometimes called experimental science to differentiate it from applied science, which is the application of scientific research to specific human needs—although the two are commonly interconnected.