A bug is an error in a software program. It may cause a program to unexpectedly quit or behave in an unintended manner. For example, a small bug may cause a button within a program's interface not to respond when you click it. A more serious bug may cause the program to hang or crash due to an infinite calculation or memory leak.

A protocol is a set of rules that governs data communication. It represents an agreement between the communicating devices. Without a protocol, two devices may be connected but not communicating, just as a person speaking Telugu cannot be understood by a person who speaks only Hindi.