Compatibility is the ability to connect things together and have them work, such as connecting a refrigerator to electrical power, a video recorder to a television, or a computer to a printer. Compatibility is an issue that is important in all branches of engineering, especially computer and software engineering. The standard solution to ensuring compatibility is the use of common, well-understood means of defining how to connect things together. These means are commonly called standards. The standards with which compatibility is concerned are the standards at the connection, or the interface. The interface is the place where the two devices join, or communicate or interact.

Within any country (for example, the United States of America) you can move from one house, take all of your electrical appliances, and plug them into the electrical system of another house with confidence that they will work without...