The American online video sharing and social media platform YouTube has had
social impact in many fields, with some individual videos of the site having
directly shaped world events. It is the world's largest video hosting website
and second most visited website according to both Alexa Internet and
Similarweb, and used by 81% of U.S. adults.
Constituting one of the world's most popular search engines, YouTube enables
inexpensive distribution of educational content, including course material
from educational institutions and "how to" videos from individuals. Worldwide
video access has spurred innovation by enabling geographically distributed
individuals to build upon each other's work, to collaborate, or to
crowdsource.