A lot of web link services run using Transmission Control Protocol or TCP as the transport layer protocol.
For these applications, the User Datagram Protocol or UDP transport layer protocol is generally used.
One example of a punch in of program that uses UDP is online video games.
Thankfully as UDP is pretty common its generally supported by internet testing software, and Nmap is no exception.
Put together the arguments that you want to use, then execute the command.
One thing to be aware of with a UDP scan is that it will take a long time.
Most requests do not receive any response, meaning the scan has to wait for the request to timeout.
Open indicates that a request got a UDP response.
Closed is a specific ICMP port unreachable issue notification.
Filtered indicates other ICMP unreachable error messages.
