The Internet is comprised of a network of computers, each of which is assigned a unique numeric address called an IP address. IP stands for Internet Protocol, the standardized method by which computers communicate with one another across the Internet.
An IP address is analogous to a telephone number in the sense that if one computer wants to communicate with another via the Internet, it finds the remote computer and initiates the communication through its IP address. Your virtual server was assigned a unique IP address at the time it was set up.