4. Feel Your Fillings. Polyurethane foam is a low-cost, easy-care cushion filling. But the more durable, high-density type can feel hard, and softer, low-density foam deteriorates more rapidly with constant use. High-resilient (HR) foam is slightly more expensive but more comfortable and long-lasting.
Ping is a program that sends a series of packets over a network or the Internet to a specific computer in order to generate a response from that computer. The other computer responds with an acknowledgment that it received the packets. Ping was created to verify whether a specific computer on a network or the Internet exists and is connected. Some have claimed that the word ping is actually an acronym for Packet Internet (or Inter-Network) Groper, deliberately contrived to play on the fact that pinging with a computer is similar to what submariners do with sonar.
For example, ping www.computerlanguage.com would yield the same results as typing in the correct numeric address. See IP address, ICMP and DNS. The term was coined when submarines first used sonar to detect enemy ships. A pinging sound was heard in the headset when a signal reflected back from an object in the water.