Online may refer to any of the following:
1. Today, being online refers to when a user, computer, or another device connects to the Internet.
Should I use "online," "on-line," or "on line" in my writing?
2. When referring to a hardware device, online is a description of when a connection is made with another device or service. When a device is online, it can send information to and receive information from the other end of the connection. For example, if your printer is online, you can send a print request to it; if it's offline, you cannot.
3. Online gaming describes a player connected to a server and playing with other real people from around the world. Online gaming requires that the user has an active connection to the Internet, allowing them to connect to the game server and see other players. If the game does not connect to another computer it is considered an offline game.