What is Deep web ?

Deep web is part of the internet that is hidden form the view.
If we can visualize internet as an iceberg the part above the surface of the water can be called the Surface Web and the rest that is unseen / under the water is called the Deep Web.

Surface Web

The surface web contains only roughly about 4% of the WWW content and surface webs content can be found by using search engines. The surface web is also known as the visible  web.

Deep Web

The deep web contains the rest of the content of the WWW content. The contents cannot be taken by simply using a search engine..Deep web is also known as the invisible web. the Deep Web is made up of peer-to-peer connections, which allow users to share files directly

 The deep web includes many very common uses such as web mail and online banking but it also includes 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.

It is very hard to measure and figure out on the exact  size of the deep web because the majority of the information is hidden or locked inside databases.secretive nature of the network has also made it a haven for criminals of various stripes, trafficking in everything from illegal drugs to stolen credit cards to child pornography. 

How to access the Deep Web ?

Information on the Deep Web cannot be accessed directly. This is because data is not held on any single page, but rather in databases, which makes it difficult for search engines to index.

Files are shared through any number of computers connected to the internet that hold the information you need. This is known as peer-to-peer networking.

In order to access the Deep Web, you need to use a dedicated browser. TOR (The Onion Router) is the most commonly used, but other options such as I2P and Freenet offer an alternative solution.