What is network port scan/services enumeration?

Network services enumeration can be used for information gathering of specific network services that are running, after the initial discovery phase.

Network services enumeration can be used to gather more information such as service name and version about a particular service that is found to be running from the initial discovery phase. This includes services such as HTTP/HTTPS, DNS, SSH, etc.

NOTE: Enumeration is different from vulnerability scanning (discussed below), as the information gathered from this phase might not lead to a direct exploit, but rather gives a better foothold on the target