Generally speaking, the DARPA research project known as ARPANET has been defined as the "beginning" of the Internet, as it was the first instance of resources shared over a wide area network. It first came to life in Sept. 1969, when the IMP server at UCLA came online.
While ARPANET did fulfill many of the computational and networking functions society has come to associate with the modern Internet, it was a far cry from today's World Wide Web, which integrates rich media and hyper-linking capabilities. Tim Berners-Lee was responsible for the original design specifications and implication of the WWW, which he released in 1989. Since then, the W3C, or WWW Consortium, has been responsible for the direction and guidance of Internet construction and development.