Wikis are easy-to-use websites that allow for collaboration. They allow users to easily create and edit web pages without additional software. Popular examples include Wikipedia, which has over 13 million articles, and internal wikis used by companies and universities for collaboration. Wikis provide benefits such as easy editing similar to a word processor, linking between pages, searchability, and the ability to make pages public or private with user accounts. They are a useful tool for students and teachers to collaborate on projects and assess understanding.