In computing, a printer is a peripheral device which makes a persistent human-readable representation of graphics or text on paper.

Software testing is an investigation conducted to provide stakeholders with information about the quality of the software product or service under test.

Software testing can also provide an objective, independent view of the software to allow the business to appreciate and understand the risks of software implementation.

Test techniques include the process of executing a program or application with the intent of finding software bugs (errors or other defects), and verifying that the software product is fit for use.

In computing, an event is an action or occurrence recognized by software, often originating asynchronously from the external environment, that may be handled by the software.

Because an event is an entity which encapsulates the action and the contextual variables triggering the action we can use the acrostic mnemonic of an event as an "Execution Variable Encapsulating Named Trigger" to clarify the concept.

Computer events can be generated or triggered by the system, by the user or in other ways.

Typically, events are handled synchronously with the program flow, that is, the software may have one or more dedicated places where events are handled, frequently an event loop.

A source of events includes the user, who may interact with the software by way of, for example, keystrokes on the keyboard.

Another source is a hardware device such as a timer.

Software can also trigger its own set of events into the event loop, e.g. to communicate the completion of a task.

Software that changes its behavior in response to events is said to be event-driven, often with the goal of being interactive.

Free software or libre software is computer software distributed under terms that allow users to run the software for any purpose as well as to study, change, and distribute it and any adapted versions.

Free software is a matter of liberty, not price: users—individually or in cooperation with computer programmers—are free to do what they want with their copies of a free software (including profiting from them) regardless of how much is paid to obtain the program.

Computer programs are deemed free insofar as they give users (not just the developer) ultimate control over the first, thereby allowing them to control what their devices are programmed to do.

The Internet is the global system of interconnected computer networks that use the Internet protocol suite (TCP/IP) to link devices worldwide.

It is a network of networks that consists of private, public, academic, business, and government networks of local to global scope, linked by a broad array of electronic, wireless, and optical networking technologies.

The Internet carries a vast range of information resources and services, such as the inter-linked hypertext documents and applications of the World Wide Web (WWW), electronic mail, telephony, and file sharing.