IP Number

The address of any machine connected to an internet network

Coded on 4 bytes

255x255x255x255 = 4,2.109 possible computers connected to the Internet

E.g.. : 192.104.32.19, ... 204.39.45.190, ...194.2.37.1

Distributed by your ISP, who got it from the ICANN (Internet Corporation for Assigned Names and Numbers)

The Internet Corporation for Assigned Names and Numbers (ICANN) is an internationally organized, non-profit corporation that has responsibility for Internet Protocol (IP) address space allocation, protocol identifier assignment, generic (gTLD) and country code (ccTLD) Top-Level Domain name system management, and root server system management functions. These services were originally performed under U.S. Government contract by the Internet Assigned Numbers Authority (IANA) and other entities. ICANN now performs the IANA function.
As a private-public partnership, ICANN is dedicated to preserving the operational stability of the Internet; to promoting competition; to achieving broad representation of global Internet communities; and to developing policy appropriate to its mission through bottom-up, consensus-based processes.

Different  class, for different type of subnet

Addresses 0 and 1 have special meaning. Roughly 0 means itself, 1 means all.

Class

No. of Networks can be served

No. of hosts each network can have

Use

A

27 -2 = 126

224 -2 = 16777214

Really big organisations

B

214 -2 = 16382

216 -2 = 65534

Big Companies, Universities (ANU : 2 class B)

C

221 -2 = 2097150

28 -2 = 254

School small organizations

D

228 -2 = 268435454

multicast addresses

 

E

227 -2 = 134217726

reserved addresses

 

Obviously not enough ! (6,500,415,220 projected to 02/28/06 at 01:09 GMT (EST+5))

IP masquerading behind proxy/firewall

IPng, IPv6 increases the IP address size from 32 bits to 128 bits

Why :-)

Countries Ranked by Population: 2006
--------------------------------------------------------
Rank Country Population
--------------------------------------------------------
1 China 1,313,973,713 : Annual rate of growth (percent)................ 0.6 / Total fertility rate (per woman)............... 1.7
2 India 1,095,351,995 : Annual rate of growth (percent)................ 1.4 / Total fertility rate (per woman)............... 2.8
3 United States 298,444,215
4 Indonesia 245,452,739
5 Brazil 188,078,227

Source : http://www.census.gov/cgi-bin/ipc/idbrank.pl and http://www.census.gov/cgi-bin/ipc/idbsum.pl?cty=IN