OAuth is an open authorization protocol, which allows accessing the resources of the resource owner by enabling the client applications on HTTP services such as Google, Facebook, Twitter, GitHub, BitBucket, and a long etc... It allows sharing of resources stored on one site to another site without using user credentials. Username and password tokens are used instead. The access to the resource can be limited by defined and approved scope.
Apache or Apache HTTP server is a free and open source web server, developed and maintained by the Apache Software Foundation. It is one of the most popular web servers in the world. Apache allows website developers to serve their content over the web and provides many powerful features that can be extended through additional modules.