There's a hidden part of the internet that is much larger than the parts of the web you use every day.
SURFACE WEB :-
The Surface Web (also called the Visible Web) is the portion of the World Wide Web that is readily available to the general public and searchable with standard web search engines. It is the opposite of the deep web. According to one source, as of June 14, 2015, Google's index of the surface web contains about 14.5 billion pages.
DEEP WEB :-
The deep web invisible web or hidden web are parts of the World Wide Web(www) whose contents are not indexed by standard web search engines for any reason.
The opposite term to the deep web is the surface web, which is accessible to anyone using the Internet.
The content of the deep web is hidden behind HTTP forms, and includes many very common uses such as web mail, online banking, and services that users must pay for, and which is protected by a paywall, such as video on demand, some online magazines and newspapers, and many more.
DARK WEB :-
The dark web is the World Wide Web content that exists on darknets, overlay networks that use the Internet but require specific software, configurations or authorization to access.
The darknets which constitute the dark web include small, friend-to-friend peer-to-peer networks, as well as large, popular networks like Tor, Freenet, I2P and Riffle operated by public organizations and individuals. Users of the dark web refer to the regular web as Clearnet due to its unencrypted nature. The Tor dark web may be referred to as onionland, a reference to the network's top-level domain suffix .onion and the traffic anonymization technique of onion routing.