What is an IP Address ?
Millions of computers and networks connected together form the internet. An IP Address is something that uniquely identifies a computer amongst the millions of computers. This is similar to the geographical address. For eg:- Google New York Chelsea Market Space, 75 Ninth Avenue 2nd and 4th Floors New York, NY 10011 uniquely identifies the address of Google. Similarly, in the internet, an IP Address like 23.34.53.23 uniquely identifies a computer in the internet. However, there is a significant difference between the two.

While the physical geographical address remains constant over a period of time, the IP Address of a particular computer can change every day or remain constant for a particular period of time. However, at any given moment of time, a single IP Address uniquely identifies a computer over the internet. This address is either assigned dynamically when the user connects to the internet through the Internet Service Provider (ISP) or a permanant (static) IP Address is allocated to the customer by the ISP .

During the early days of internet, the addressing system for computers connected over the internet was devised to have the following format

a.b.c.d (For example:- 155.35.90.256)

where the alphabets a,b,c and d can take the values from 0 to 255. So, theoretically, the total number of possible addresses that could be allocated was

256 x 256 x 256 x 256 = 4294967296

This number was thought to be a huge number that could never exhaust. However, with the explosion of the number of computers and network devices connected to the internet, the number of IP Addresses available for fresh allocation began to deplete rapidly over the past few years. Another reason for rapid depletion of IP Addresses was, unused IP Addresses are not being returned to IANA, the parent organization that oversees IP Address allocations. Computer scientists faced a fresh problem of devising a new addressing system that can take care of much more computers connecting to the internet.

A new internet addressing system was born called the “IPV6? to cater to ever increasing number of computers and other network devices connected to the internet. This method supports allocation of a total of 2128 (approximately 340 undecillion or 3.4×1038 ) addresses. IPV6 addresses are generally written in hexadecimal format. A typical example of an IPV6 address is 2001:0db8:85a3:0000:0000:8a2e:0370:7334 . An IPV4 address can also be written in hexadecimal format or as a pure integer. Major internet providers have braced themselves to supports to IPV6 only clients. Some network applications require minor modifications to support the IPV6 system, while others may need major modifications.

What information can be found from an IP Address ?
By performing an IP Lookup, it is possible to estimate the location, ISP, domain name amongst other things from a given IP Address. It is also possible to check if the server is a proxy server. It is also possible to trace e-mail source by performing an IP lookup on the source IP of the email.