In the context of an HTTP transaction, basic access authentication is a method for an HTTP user agent to provide a user name and password when making a request.
HTTP Basic authentication (BA) implementation is the simplest technique for enforcing access controls to web resources because it doesn't require cookies, session identifier and login pages. Rather, HTTP Basic authentication uses static, standard fields in the HTTP header which means that no handshakes have to be done in anticipation.
Source and more information at https://en.wikipedia.org/wiki/Basic_access_authentication
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