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PortNumbers.info is a free online port number database that provides information about different port numbers and how to work with them.

What Are Port Numbers?

Port numbers are numerical identifiers used in networking to distinguish different services or applications running on a device. They act as communication endpoints, allowing computers to direct data to the correct application. For example, when you visit a website, your browser communicates with a web server through port 80 or 443, which are designated for HTTP and HTTPS traffic, respectively. In essence, port numbers ensure that data packets are sent and received by the correct service on a device.

Who Manages Port Numbers?

The Internet Assigned Numbers Authority (IANA) is responsible for managing port numbers. IANA has established a system for categorizing port numbers into three ranges: well-known ports (0-1023), registered ports (1024-49151), and dynamic/private ports (49152-65535). Well-known ports are reserved for standard services like HTTP, FTP, and SMTP, while registered and dynamic ports are typically used for custom applications or temporary connections. By assigning port numbers, IANA ensures a standardized, conflict-free environment for networking across the internet.

Importance and Common Use

Port numbers play a critical role in ensuring smooth communication between devices and applications. Each port is associated with a specific protocol, allowing devices to multitask by handling multiple requests simultaneously without confusion. For instance, a single computer can send emails, browse the web, and download files at the same time because each service operates on a different port number. This structure helps maintain the organization and efficiency of the internet, making port numbers essential for daily online activities.