Here is the detailed explanation:
1: The Internet is a Big Collection of Computers and Cables.
The Internet is named for "interconnection of computer networks". It is a massive hardware combination of millions of personal, business, and governmental computers, all connected like roads and highways. The Internet started in the 1960's under the original name "ARPAnet". ARPAnet was originally an experiment in how the US military could maintain communications in case of a possible nuclear strike. With time, ARPAnet became a civilian experiment, connecting university mainframe computers for academic purposes. As personal computers became more mainstream in the 1980's and 1990's, the Internet grew exponentially as more users plugged their computers into the massive network. Today, the Internet has grown into a public spiderweb of millions of personal, government, and commercial computers, all connected by cables and by wireless signals.
No single person owns the Internet. No single government has authority over its operations. Some technical rules and hardware/software standards enforce how people plug into the Internet, but for the most part, the Internet is a free and open broadcast medium of hardware networking.
Here is a conceptual diagram of the Internet and how it contains many forms of online communications
2: The Web Is a Big Collection of HTML Pages on the Internet.
The World Wide Web, or "Web" for short, is a massive collection of digital pages: that large software subset of the Internet dedicated to broadcasting content in the form of HTML pages. The Web is viewed by using free software called web browsers. Born in 1989, the Web is based on hypertext transfer protocol, the language which allows you and me to "jump" (hyperlink) to any other public web page. There are over 65 billion public web pages on the Web today.
Next: Internet 101.
Next: Understanding URL and Internet Addresses
Next: What is "P2P" Networking?
Next: The Internet Search Handbook for Newbies