In this day and age people want to know the inner workings of how stuff really works and how their computer connects to the internet is a popular subject. The more you know about how your computer connects to the internet the better off you will be with managing and protecting your system.
TCP facts and information
TCP is short for Transmission Control Protocol. A TCP connection is a steady connection stream and is usually uninterrupted. A TCP/IP connection is a type of connection that one computer must know the IP address of another to designate the "delivery" location to setup a seamless connection between the two. TCP/IP is a very common type of internet protocol connection used and is a common term used often as it is almost a standard for a basic internet connection. During a TCP connection of two computers they both stay connected until the transfer of data is completed. Once a transfer is completed the two computers disconnect. This provides a very fast and safe environment for sending or receiving data.
UDP facts and information
The UDP acronym is short for User Datagram Protocol. A UDP connection is not a direct connection between two computers such as a TCP connection. During a UDP connection the data is grouped into a packet of information and sent out with its programmed destination through other (helping) services on the way. UDP rests on the assurance that the services in between the transport will keep sending the data to reach its end point. This method is not as reliable as TCP as it is not always guaranteed to reach its destination. Usually information sent over via UDP can be re-tried in the case that it does not reach the destination.
TCP Ports and UDP Ports - The Techie Stuff
A TCP Port functions similar to a Satellite receiver does to your TV. It takes up one port that is designated for the one device and the specific signal is pre-programmed by the satellite company to decipher which Satellite receiver to send certain channels too. This is just like an IP address on a computer, it is specific to each computer to tell any type of service where to route data. A TCP or UDP port once used by one device cannot be used by any other devices. With any given IP address you have up to 65,535 TCP ports available and 65,6535 UDP ports available. Technically that's 131,070 ports available for data sending and receiving.
TCP Ports and UDP Ports In non-techie terms
Think of a web server as a big cardboard box. Imagine two computers on opposite ends of the big box as the computers that need to connect to each other. Now visualize a wire attaching one computer to the cardboard box and another separate wire connecting the other computer to the same large cardboard box. You poke holes in the boxes for the wire attachment and this serves as your port. In either computer box you can poke up to 65,535 holes but that hole can only have one wire each. Once a wire is connected from computer to server to other computer, you have a complete connection. Usually with a UDP connection transferring information from one computer to another relies on the server. With a TCP connection it will directly connect with the computer at the other end.
Port assignment is made within software applications such as your web browser. Certain types of servers use pre-assigned ports such as an FTP server. FTP servers usually use TCP Port # 20 and 21. The Ports are assigned to prevent conflict with data traveling on other ports. Think of this as a large highway with heavy traffic, you do not want to mix slow traffic in one lane with the fast lane, you will have problems. To prevent one application from registering the same port numbers as another, software developers register their number with the IANA Registry. The IANA Registry keeps a log of all registered port numbers of software applications to prevent any kind of conflict amongst a program using someone else's assigned port number.