Internet

The Internet is the biggest world-wide communication network of computers. The Internet has a lot of smaller domestic, academic, business, and government networks, which together carry many different kinds of information. The short form of internet is the 'Net'. The World Wide Web is one of its biggest services. It is used by countless people all over the world.

Logo of DARPA, an organization funded by the US government, which helped develop the Internet

The Internet was developed in the United States by the Department of Defence Advanced Research Projects Agency (DARPA). The Internet was first connected in October 1969^[1] and was called ARPANET. The World Wide Web was created at CERN in Switzerland in 1990 by a British (UK) scientist named Tim Berners-Lee.

Today, people can pay money to access the Internet from internet service providers. Some services on the Internet cost nothing to use. Sometimes people who offer these free services use advertising to make money. Censorship and freedom of speech on the Internet can be controversial.

Services

Visualization of Internet routing paths

The Internet is used for many things, such as electronic mail, online chat, file transfer and other documents of the World Wide Web.

The most used service on the Internet is the World Wide Web (which is also called the "Web" or “www”). The web contains websites, including social media, blogs, and wikis like Wikipedia. Webpages on the Internet can be seen and read by anyone (unless the page needs a password, or it is blocked).

The second biggest use of the Internet is to send and receive e-mail. E-mail is private and goes from one user to another. Instant messaging is similar to email, but allows two or more people to chat to each other faster.

Some governments think the internet is a bad thing, and block all or part of it. For example, the Chinese government thinks that Wikipedia is bad, so often no one in China can read it or add to it.^[2] Another example of the internet being blocked is in North Korea.^[3] Some parents and schools block parts of the Internet they think are bad for children to see.

Dangers

The Internet makes communication easy. Yet, communication can be dangerous, too. People often send secret information, and sometimes other people can steal that information. They can use the Internet to spread lies, steal secrets, or give dangerously bad advice. For example, Facebook has had some problems with privacy settings.

Some websites may trick people into downloading viruses that can harm a computer, or spyware that spies on its users (looks at what they are doing and tells someone else).
E-mails can have harmful files with them as "attachments".^[4]
In internet chatrooms, people might be preying on others or trying to stalk or abuse them.
The Internet contains content that many people find offensive , as well as content intended to be offensive.
Criminals may steal people's personal information or trick people into sending them money.

Internet Media

A sketch of the ARPANET in December 1969. The nodes at UCLA and the Stanford Research Institute (SRI) are among those depicted.
T3 NSFNET Backbone, c. 1992
ICANN headquarters in the Playa Vista neighborhood of Los Angeles, California, United States
2007 map showing submarine fiberoptic telecommunication cables around the world
Packet routing across the Internet involves several tiers of Internet service providers.
Number of mobile cellular subscriptions 2012–2016
As user data is processed through the protocol stack, each abstraction layer adds encapsulation information at the sending host. Data is transmitted over the wire at the link level between hosts and routers. Encapsulation is removed by the receiving host. Intermediate relays update link encapsulation at each hop, and inspect the IP layer for routing purposes.
A DNS resolver consults three name servers to resolve the domain name user-visible "www.wikipedia.org" to determine the IPv4 Address 207.142.131.234.
Creating a subnet by dividing the host identifier