Ping uses ICMP (internet control message protocol) to send a small packet of data to a specific address which responds by sending an 'echo' and the response time can be given in textual or graphical format.
You can use it to test the availability of web site to see if it's online. In Windows click Start, Run and enter cmd to open a DOS window. In the window type "ping
www.websiteaddress.com"
This will send continuous four ping packets to the address like this:
C\>ping
www.bbc.co.uk
Pinging
www.bbc.net.uk [212.58.224.114] with 32 bytes of data:
Reply from 212.58.224.114: bytes=32 time=21ms TTL=247
Reply from 212.58.224.114: bytes=32 time=21ms TTL=247
Reply from 212.58.224.114: bytes=32 time=16ms TTL=247
Reply from 212.58.224.114: bytes=32 time=25ms TTL=247
Ping statistics for 212.58.224.114:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 16ms, Maximum = 25ms, Average = 20ms
Use 'ping -t
www.websiteaddress.com' for continuous pings.
You are correct in that response times depend on which continent and which country the server resides. Also, any problems on the internet or with your ISP can affect the response times or even prevent access completely.
Another command that shows the route the date is taking is "traceroute". For some reason Microsoft decided to abbreviate this command in Windows to "tracert"
So c\ tracert
www.bbc.co.uk will show you the path the BBC web site.