A mobile device (or handheld computer) is a small computing device, typically, small enough to hold and operate in the hand and having an operating system capable of running mobile apps.

These may provide a diverse range of functions.

Typically, the device will have a display screen with a small numeric or alphanumeric keyboard or a touchscreen providing a virtual keyboard and buttons (icons) on-screen.

Many such devices can connect to the Internet and interconnect with other devices such as car entertainment systems or headsets via Wi-Fi, Bluetooth or near field communication (NFC).

Integrated cameras, digital media players, mobile phone and GPS capabilities are common.

Power is typically provided by a lithium battery.

In computer networks, to download is to receive data from a remote system, typically a server such as a web server, an FTP server, an email server, or other similar systems.

This contrasts with uploading, where data is sent to a remote server.

The terms "online" and "offline" have specific meanings in regard to computer technology and telecommunications in which "online" indicates a state of connectivity, while "offline" indicates a disconnected state.

Common vernacular extended from their computing and telecommunication meanings and refers specifically to an Internet connection.

Lastly, in the area of human interaction and conversation, discussions taking place during a business meeting are "online", while issues that do not concern all participants of the meeting should be "taken offline"—continued outside of the meeting.