Forward compatibility is a design principle in which a program or piece of hardware is developed to remain functional in the future with new software or devices. For example, a computer program is typically written in code that allows it to work with an Operating System (OS) and hardware that is current at the time of its release. A developer creating a program with forward compatibility in mind tries to ensure that it will also be able to function several years later with a new OS and different hardware. This can be quite difficult to ensure, however, though certain methods can be used to make the process simpler.
The basic idea behind forward compatibility, is to try to ensure that something remains useable in the future. While this is fairly simple in some settings, within the computer and Information Technology (IT) industries it can be rather difficult to achieve. A software developer often requires that programmers ensure the code they use in making an application remains relevant and useable with changes that are likely to occur. The unpredictable nature of some technological evolutions, however, makes forward compatibility difficult, as something that seems straightforward right now may be much more complex in a few years.
One way in which forward compatibility can be achieved is through the use of different software versions that can all be ran together. This way, a developer working on an application that runs with version 1.2 of a program, can simply require that users have 1.2 even if they might also have version 2.5 of that same software. Multiple versions can be a problem, however, if an older one is found to have major security flaws or other problems not easily resolved. At that point, the older versions are likely to be abandoned and the forward compatibility has been lost.
Many software developers ensure that patches and similar updates are used to maintain forward compatibility for their programs. If a package is developed to work with a particular OS, and then a new version of that OS is introduced, the developer of that package is likely to ensure it can still function with it. Patches are often used to add to the base programming, allowing a developer to maintain functionality without a completely new release.
Similar to forward compatibility, backward compatibility is the option for a newer application or file to run on older systems. A new version of a word processing program, for example, might use a file type that is quite different from older versions. Without proper backward compatibility, someone can create a file in the new version, but be unable to access it through an older one. Both forward and backward compatibility are important, as they keep data accessible and allow users to feel comfortable upgrading equipment and software.