|ping (Packet Internet Groper) is a basic Internet utility program that sends a small amount of data (ICMP packet) to test connectivity between network devices. The verb ping refers to using the ping command to test whether a particular IP address exists and can accept requests.
Ping can be used to check latency: a ping response from a remote host contains RTT (round-trip-time) as well, which is a measure of the delay (latency) of packets transfered between you and that network node.
Ping can be used to find the IP address of a domain: if you ping the hostname, you will see the dot address (such as 188.8.131.52) for that domain name.
Ping can be used to identify packet loss: when you ping a host/IP address several times, if the number of packets transmitted and the number of responses received are not equal there is some packet loss present. This might not be a very accurate measurement however, since some routers are configured to give a very low priority to (consecutive) ICMP pings.