IP Address is a unique numerical identification number assigned to a computer which is member of a network. IP (Internet Protocol) address can be either private or public. Computers that are connecting to Internet must either have a public IP address or use a proxy server to connect to the Internet.
For ex: if you are connecting to Internet/ISP using a broadband router, your computer is assigned a local/private IP address while your router which establishes a connection with your ISP gets a public IP address. So, when you try to find what your IP address is, you will see the public IP address of your router but not the private IP address of your computer which is internally using the router as its gateway to connect to Internet. The IP address of your computer, in most home networks, is assigned by the router using the DHCP protocol.