英语作文:“on line”

The terms online and offline (also on-line and off-line) have specific meanings with respect to computer technology and telecommunication. The concepts have however been extended from their computing and telecommunication meanings into the area of human interaction and conversation, such that even offline can be used in contrast to the common usage of online (e.g., "I bought that shirt offline").

In computer technology and telecommunication, online and offline are defined by Federal Standard 1037C. They are states or conditions of a "device or equipment" or of "a functional unit". To be considered online, one of the following must apply to a device:

Under the direct control of another device
Under the direct control of the system with which it is associated
Available for immediate use on demand by the system without human intervention
Connected to a system, and is in operation
Functional and ready for servic