Your IP address is fundamental to the way that the Internet works. Your computer is able to use the internet after its IP has been asigned by your internet service provider. Computers communicate over the Internet using IP addresses through a standard set of protocols, and the IP (Internet Protocol) address is the numbered location of your computer's connection to the Internet. The protocol describing how the Internet Protocol works is called Transmission Control Protocol (TCP).
TCP allows the transmission of digital files as data through copper wires attached to your computer, and over the fiber of the internet backbone, through the air to phones, or through the air to laptops connecting with WiFi ata coffee shop. Controlling how all these computers communicate, it's the assignment of IP addresses between computers which makes it all possible. That's why when you load this page, this computer can tell you what your IP address is.
Where Do These Numbers Come From?
IP Address numbers need to be organized so that everything works the way that it does. The international non-profit organization which governs number assignment is called ICANN (Internet Corporation for Assigned Names and Numbers). The charter for the organization states its focus as to "Manage Internet Protocol numbers and Domain Name System root."
ICANN also manages the Domain Name System, which is a technical service that reserves and translates IP addresses into words for people to remember more easily. It's easier to think of loading searchreturn.com than to try to spell out the IP address of the computer that publishes searchreturn. When you type a domain name into your browser address bar it is first translated to the IP address so that TCP can resolve the website for loading it with your browser.
Who controls my IP right now?
There is a simple service known as 'whois' to find out that type of information. The information published here as your IP should look familiar to you as pertaining to the Internet Service Provider you are currently using. They control which IP address you are assigned when you sign on to the internet. Knowing how IP addresses are used for the internet is the first step in digital forensics. IP forensics can be used to record and tracking Internet activity.
Want to know a Google IP addess?
Look at the cache version of this page at Google where you will find the IP address of Google's crawler which fetched this page. Doing this is called spider spotting.