IP stands for Internet Protocol. The IP Address is a number that identifies a computer or router. In order for computers to communicate on a network or on the internet, each computer must be identified somehow, and this is done using private IP addresses (for local networks) and public IP addresses (for the internet).

An IP address, when it comes to the internet, is a number that represents your router. When you connect, this number sends commands out to another IP address to get information.

For example, when you visit a popular website (like Google), your computer doesn't actually send a request for google dot com. The real request that it sends is the IP address of Google's server.

The word-based website addresses (such as www dot whatever dot com) that we use are just there to make the internet more convenient and user-friendly to the average person. In reality, all websites are sending and receiving information using numerical addresses called IP addresses. DNS servers act as liaisons and convert word-based addresses into number-based IP addresses when you go online.

An IP address comprises four groups of numbers separated by a period (or dot or decimal point, whatever you want to call it). There are over 4.2 billion combinations of numbers that can create a unique IP address.

Two Main Types of IP Addresses

There are two main types of IP addresses you may encounter.

One is your private IP address, also known as a local IP address. This is the address that your computer and router use to communicate with each other inside your home.

Private IP addresses are not reachable from the outside world or the internet. The most common private IP address is 192.168.1.1. Most routers default to identifying themselves on your local network as either that address or 192.168.2.1.

A situation where one might need to know their private IP is when port forwarding. Certain online games and other online applications need to access ports on your local computer but a firewall prevents such port traffic.

To bypass this, there is a setting in your router called port forwarding, persistent port forwarding or tunneling wherein your router makes an exception and allows traffic on a certain specified port. The port must be forwarded from router to the local IP (private IP) of your particular computer in order for port-based applications to work.

The other main type of IP address is called a public IP. A public IP address is the one that your router uses to connect to the internet. One instance where a public IP address is important to know is when using a VPN (virtual private network) or VNC (virtual network computing) application.

VPN and VNC applications allow you to create a virtual network that functions just like your local network, with another computer somewhere on the internet (a friend or colleague's office or home, even far away, for example). VNC apps (such as RealVNC) also allow you to control another computer remotely. You can see its screen, control its keyboard and mouse functions and so on.

These applications would not be possible without the use of Public IP addresses for the main connection, and Private IP addresses for the port forwarding to your local computer.

If you do use an application where port forwarding is required, be sure that the port has been opened not only on your router's setup page (usually under security or gaming tabs) but also in your windows firewall. You'll also need to check your anti-virus, anti-spyware, and other similar programs to see if they block ports as well.

Public IP Addresses and Concerns about Privacy and Security

You'll also be interested to know that any activity you do online is traceable back to your Public IP address. This can be averted to some degree by using a proxy server to access the internet. However, no matter how private the internet feels when you are at home, it is a public place. Let your behavior online reflect this lack of true privacy!