A network port is usually represented by a number which is assigned to a protocol (rules according to which information is sent and received over the Internet). Network ports are essential since they prevent conflicts between various protocols, and they can ensure a network’s security since blocking a port means you will prevent a protocol from being active on the network.
A good example of a port is port 53 which is responsible for DNS traffic, specifically associating a website name with an IP address so that you can access websites without having to know their IP addresses.