How do you find out which port is being used by which process?

To find out which port is being used by which process, you can use the command line tool netstat along with -ano flags on Windows, or -tuln on Linux. For Windows, run netstat -ano in Command Prompt to see a list of active connections and their associated process IDs (PIDs). On Linux, use sudo netstat -tuln or sudo lsof -i -P -n to view similar information. To identify the process by its PID, you can use tasklist on Windows or ps -p <PID> on Linux.