As a noun, a hack is the source code of a program. For example, the phrase "it must be done through a hack" means someone has to write programming code to solve the problem because there is no pre-written software that does the job.

As a verb, hack refers to writing a small program or adding code to an existing program to solve a problem in a hurry. A hack often implies writing in a low-level programming language rather than a high-level macro language or application generator that is oriented to the user. It may even mean writing and deploying a patch in machine language. See hacker, patch and machine language.

You're Not Supposed To!
A hack may refer to an enhancement made to a computer-based appliance that is not at all user programmable, such as a video game, music player, TV set-top box or cellphone. For example, a digital media hub (media extender) could be modified to play back additional audio or video formats not supported by the unit. This kind of hacking is done by the serious enthusiast, who first has to find a way to expose the software.

It may require opening the box to reach the chips, using tools such as a screwdriver, wire strippers and soldering iron. For example, to make the iPhone work in a non-AT&T network, the first step in 17-year-old George Hotz's hack required applying voltage to one line on its circuit board. It meant scraping the surface of a single wire trace without breaking the line and soldering a wire to it, a very delicate operation. Subsequently, far less extreme methods were found to successfully unlock the phone.