The Internet was first created around 1969 when UCLA and Stanford made a network connection between two of their computers and tried to type in the word "login"
I believe one of the most important breakthroughs was when the internet became commercial in the mid 1990s, for that is when it started increasing in popularity and was starting to be used by normal people other then just Universities.
Once the internet became commercial companies such as AOL became very popular and an average household was able to connect to the internet and help it grow at over 100% a year in the late 1990s.
I belive the person who had the largest impact on todays internet was Tim Berners-Lee, for he created one of the first web browsers and editors WorldWideWeb.
In 1994, Berners-Lee founded the World Wide Web Consortium (W3C) at the Massachusetts Institute of Technology. It comprised various companies that were willing to create standards and recommendations to improve the quality of the Web. Berners-Lee made his idea available freely, with no patent and no royalties due. The World Wide Web Consortium decided that their standards must be based on royalty-free technology, so they can be easily adopted by anyone
The Internet Corporation for Assigned Names and Numbers (ICANN) is the authority that coordinates the assignment of unique identifiers on the Internet, including domain names, Internet Protocol (IP) addresses, and protocol port and parameter numbers. Visit the ICANN oficial website here.
These are some of the top websites that have changed how users use the internet of today.