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Internet & Networking Terminology

A. Internet — A Network of Networks​

The Internet is essentially a network of networks.

In the early days, it connected a small number of computers, such as university mainframes. Today, billions of devices and many different networks are interconnected through the Internet.

The Internet is a network of networks.

B. Intranet — A Private Network​

An Intranet is a private network commonly used inside companies or organizations.

It may still connect to the outside Internet, but access from outside is restricted.

Organizations commonly protect their intranets using technologies such as:

  • Firewalls
  • VPNs

The goal is to allow internal communication while controlling who can access the network from outside.

C. LAN — Local Area Network​

LAN stands for Local Area Network.

A LAN connects devices within a relatively small physical area, such as:

  • A home
  • An office
  • A classroom
  • A building

Because the devices are physically close and communicate through the same local network, latency is generally very low.

A classic example is a LAN party, where multiple computers connect to the same local network to play games together.

D. WAN — Wide Area Network​

WAN stands for Wide Area Network.

Unlike a LAN, a WAN connects networks across a larger geographical area.

For example, it may connect networks located in multiple buildings or locations.

The instructor notes that the term is heard less often in everyday development compared with concepts such as Intranet.

E. IP — Internet Protocol​

IP stands for Internet Protocol.

The Internet works because different systems follow common standards and protocols.

Internet Protocol defines rules for addressing devices on a network.

These rules define things such as:

  • What an IP address looks like
  • How addresses are structured
  • How devices are identified

A protocol is a set of agreed-upon rules that allows different systems to communicate.

F. IP Address​

An IP address is a network address assigned to a network interface, such as a computer's Wi-Fi or Ethernet interface.

It allows devices to identify where network traffic should be sent.

Devices behind a router often use local addresses such as:

192.168.x.x

These are local/private IP addresses.

The router allows multiple devices with different internal IP addresses to share a connection to the wider Internet.

In a typical IPv4 home network, devices use private IP addresses behind a router. The router commonly uses Network Address Translation (NAT)—more specifically, port-based NAT such as NAPT/PAT—to let many private connections share one public IPv4 address.

Multiplexing is the broader idea of combining multiple communication flows over a shared resource. NAT/PAT is the specific address-and-port translation mechanism that commonly enables this sharing in IPv4 networks. They are related concepts, but they are not the same thing.

The important idea is that the Internet works because different networks and devices follow shared standards and protocols, allowing them to communicate with each other.