What does TCP use the concept of ports for?

TCP uses the concept of ports primarily to support multiple concurrent applications running on a single device. Each application that requires a network connection can be assigned a unique port number, which allows the Transmission Control Protocol to distinguish between various data streams that may come from different applications or services.

For instance, when a web browser connects to a web server, it typically uses port 80 for HTTP or port 443 for HTTPS, while a file transfer might use port 21 for FTP. This differentiation is crucial because it ensures that the data packets received by the device can be directed to the correct application for processing. Consequently, multiple applications can effectively communicate over the network at the same time without interfering with one another, facilitating smooth and efficient use of network resources.

In summary, the use of ports by TCP enhances multitasking on devices and is integral to the proper functioning of networked applications.