Technology Primer: The Combadge

The combadge has become the ubiquitous symbol of Starfleet in the 24th century.  More than just the insignia of the organization, it has evolved to the point where it is now the technological tether for an officer to his ship.
Circuitry miniaturization allowed for the standalone technology of the communicator to be implemented into the badge that has been standard on Starfleet uniforms since its inception.  Worn on the left breast of the uniform, its primary function is to provide communication, be it onboard, ship-to-shore, or directly with another combadge.  Due to its size, the combadge has limited transmission range, but the signal can be boosted by a starship’s communications systems.  As part of its communications abilities, it also contains a fully-fledged universal translator circuit.
An officer engages the combadge by tapping on it once.  This activates its circuits and makes it ready to receive a command.  The device is deactivated, or placed into a standby state by double-tapping it.
Another important function of the combadge is as an aid to the transportation process.  The circuitry of the combadge allows the transporter system to establish a stronger lock on an attached or nearby object, thereby allowing a quicker and more precise transport.
The combadge also allows for vocal interaction with the ship’s computer, where access to a console or panel is impractical or impossible.
The combadge contains many useful components, and with a healthy dose of ingenuity, it can be modified to perform any number of functions in an emergency situation.  A few examples of past modifications include subspace distress beacon, and field generator.
For practical as well as symbolic reasons, when an officer has been relieved of duty, their combadge is confiscated.   It is too much a risk to allow an incarcerated or disgraced officer access to the components and abilities of the device.
Arguably, the combadge has become the most indispensable piece of technology for the modern-day Starfleet officer.