A port is a software construct often used for multiplexing an IP address. Like a single apartment building having multiple apartments, a single IP address can have multiple ports.
Port numbers are appended to the end of an IP address with a colon to form a socket. In the following example, a Postgres database, a Node.js API and a React frontend application each share localhost but open different sockets—listening on ports 5432, 8080 and 3000, respectively:
http://127.0.0.1:5432 (database)
http://127.0.0.1:8080 (API)
http://127.0.0.1:3000 (frontend)
The HTTP Port specified in your Uffizzi app configuration is the port at which your app is listening for incoming HTTP requests. By default HTTP Port is set to 80 but can be changed. When a user or another app sends an HTTP or HTTPS request to your app (e.g. https://www.example.com), your environment's load balancer will route the request from port 80 (HTTP) or 443 (HTTPS) on the load balancer to the port your app is listening on. For app environments that have HTTPS setup, the environment's load balancers will automatically negotiate the TLS handshake and forward traffic from port 443 on the load balancer to the HTTP Port your app listens on.