A "ping" sends signals (packets) to another computer on the Internet to see if they send a return or an "echo". If all the signals "timeout" the computer that is trying to be reached may be disconnected from the Internet or at least unreachable from your computer if the Internet connection is down, etc. This feature only checks a computer connected to the Internet, it cannot verify the validity of an e-mail address. It also cannot check a specific web page, but it can check the primary domain name to see if it is connected (example: www.google.com is valid but www.google.com/index.htm is not). Pings are often used by computer consultants to ensure that your internet connection can access well-known sites, with acceptable response times. For example, if a ping is sent to www.google.com through your Internet connection and the request "times out", chances are that there is an issue with your computer's connection or with your Internet provider's services at that moment, because Google is seldom ever off-line.