Just as no one owns the whole Internet, no single agency determines how it operates from day to day. They also maintain public databases anyone can use to look up users and computers on the Internet. For example, RFC 822 established the format of the headers you see in every Internet email message. Each Internet provider or site decides what its users may do on the Internet, what standards it will comply with, and what kind of information it will receive from and transmit to the world. Providers and users who ignore these guidelines may find themselves shunned by the rest of the Internet community.
Information is transmitted over the Internet in the form of packets.
Each packet gets handed along the net by computers that have been designated as routers, until it reaches its destination machine. There, the packets are reassembled into the piece of information and sent to the appropriate user. The mail server acts like a local U.S. Post Office. It receives each packet in our message and checks the address. If this were a mail message to another Simply Internet user, the mail server would send it straight to their mailbox.