"Online" and "offline" are terms used in telecommunications. If a computer or a user is connected to the Internet, it is said to be "online". A website, for example, is online, because it is on the Internet.
If something is not online, it is said to be "offline". If a system is offline, it is in a disconnected state.
Online can also mean that something is set up correctly and ready to what it is supposed to do. For example:
- A computer printer is online if it has electricity, is turned on, is connected to the computer and has paper in it. Once each of those things is true, then the printer is online and ready to print.
- A government program is online when it has the equipment and people it needs to do whatever job it was created to do.
Online and offline Facts for Kids. Kiddle Encyclopedia.