It is a source of written articles, research papers, and books. In this sense it's a Digital Library. But it's also a source of sound files, movies, music, advertising, art work and photographs. Each item you can access has a unique name, called a "resource locator", hence the term URL.
The Internet is a network of computers, each one at the end of a communication "wire" although that may be a fibre cable, or a radio connection. These computers are independent from each other. Each one has equal power. The main difference between all these computers is the person operating each one. There are huge banks of computers called servers, that deliver much of the information on the Internet. While those are powerful in the sense of capacity to process information, they are essentially dumb machines. Your computer with YOU driving it is more important.
The Internet is also a social network that allows all those people who work at their computers to communicate with each other in a personal way. People begin by linking only to people they know well, but with experience you soon learn that there are great benefits from linking to people you do know at all. Online social networks allow you to meet suitably qualified people.
Golden ages of the past have always been preceded by the development of intellectual hothouses where ideas flourished and clashed, and where debate was cherished and fostered. Some parts of the Internet are like that. Many hope this points to a better future for mankind.