ICMP means Internet Control Message Protocol and is always coupled with the IP protocol (There are 2 ICMP variants one for IPv4 and one for IPv6.) echo request and echo response are the two operation codes of ICMP used to implement ping.
It is the protocol the routers in neighboring autonomous systems use to identify the set of networks that can be reached within or via each autonomous system.
Secondary market refers to market where securities are traded after being initially offered to the public in the primary market and/or listed on the stock exchange.
Glycogen is the storage form of glucose in animals and humans which is analogous to the starch in plants. Glycogen is synthesized and stored mainly in the liver and the muscles.