What is Internet?
Definition of Internet.
1. Internet is a global system of interconnected computer networks that interchange data by packet switching using the standardized Internet Protocol Suite (TCP/IP). – Wikipedia 
2. The internet is a large network that connects together smaller networks all over the globe. – Computer Essentials 2008 
3. Internet provides, uses or makes accessible, either publicly or privately, high level services layered on the communications and related infrastructure described herein. – dotnetheaven.com 
From my opinion, internet stand to a “International Networking” that links from other computer device(computer, PDA, mobile phone, etc) to other computer device so we can share information, do business, military and many more using special and unique compatible protocols.
Who own the internet?
From the wikipedia website  dotnetheaven.com , and Computer Essential 2008 books , I assume that nobody owned the internet but there is some organization that influenced internet services.
The World Wide Web Consortium (W3C) - HTML 
The Internet Engineering Task Force (IETF) - evolution of the Internet. 
The Internet Engineering Steering Group (IESG) - managing IETF activities. 
The Internet Architecture Board (IAB) 
The Internet Society (ISOC) 
The Internet Assigned Numbers Authority (IANA) - responsible for assigning IP addresses and domain names. 
 Computer Essentials 2008, Complete Edition, Timothy j. O’Leary, Linda l. O’Leary. McGraw Hill