1.1 What is the Internet

1.	The Internet is made up of unlimited number of computers and networks connected with each other around the world.
2.	It can be thought as a network of networks or an internetwork.
3.	It acts as a single huge network for transporting, sharing and exchanging content (data, information and knowledge).

The Internet Hierarchy

1.	An analogy to describe the Internet hierarchy is a multi-level river system where small branches feed medium-sized streams which in turn feed large rivers:

	a)	The Internet’s backbone is the river,
	b)	Network Access Points (NAPs) are the medium-sized streams.
	c)	Internet Service Providers (ISPs) with the user and organization hosts they support are the small branches.

2.	The Internet hierarchy main components are illustrated in Figure 1.1 and described below:

1.1 What is the Internet

Backbone: multiple networks, routing services, and other servers resources with multiple redundancy capabilities to keep content online available, reliable and secure.>

a)

The Internet backbone is composed of high speed connections that link together large networks over the Internet.

3.	NAPs: Network Access Points (NAPs) are public network exchange facilities where ISP's can connect with one another in peering arrangements.

	a)	These NAP's are key components of the Internet backbone because the connections in them determine how the traffic is routed.
	b)	They are also the points of most Internet congestion as large amounts of traffic go through them.

4.	ISPs: Internet Service providers (ISPs) provide Internet connection services to end users and organizations.

	a)	ISPs can be regional or local.
	b)	A regional ISP is connected directly to a NAP.
	c)	A local ISP depends on a regional ISP to provide its services.

1.1 What is the Internet

Figure 1.1 Typical Internet Hierarchy Model