Ping is one of the most common utilities, found on virtually every network computer for the past 20 years. If you are running Windows for WorkGroups, Windows 95, XP or Windows 7 you should have ping available to you. Similarily if you run Ubuntu Linux, Fedora or one of the hundreds of other Linux distributions you will also have ping available in most cases. Apple folks will usually have it though I am not sure if its installed on a itouch, on an ipad you may need to app store it similarily on Android. You get the idea. It is a testing tool to discover if a system is reachable over the network and reports a response time that can be used to diagnose network issues.
A system that does not respond could be in a few different states, the computer may be fine with the problem lying somewhere in the network path between the two systems. Another reason for a no response is if a firewall along the way is dropping ICMP packets. This will also result in no response, with the system still being up and running.
Here is the default output from Ubuntu Linux and a ping to www.google.com
PING www.google.com (184.108.40.206) 56(84) bytes of data.
64 bytes from www.google.com (220.127.116.11): icmp_req=1 ttl=56 time=17.0 ms
64 bytes from www.google.com (18.104.22.168): icmp_req=2 ttl=56 time=10.9 ms
64 bytes from www.google.com (22.214.171.124): icmp_req=3 ttl=56 time=13.2 ms
64 bytes from www.google.com (126.96.36.199): icmp_req=4 ttl=56 time=16.2 ms
64 bytes from www.google.com (188.8.131.52): icmp_req=5 ttl=56 time=8.98 ms
The online Ping Test
offered here is tidied up a bit to make the results prettier, the above example shows the raw output. If you want more information try the Ping entry at Wikipedia
otherwise start testing!