new to a language (and especially those new to programming) will often attempt to manually write many functions for which a more robust and optimized equivalent already exists in the standard library or other easily available libraries. While this can be useful as a learning exercise when done unknowingly the result is often less readable, less reliable, less tested and less optimized software which takes longer to write, test, maintain, and debug. Related phrases Reinventing the square wheel is the practice of unnecessarily engineering artifacts that provide functionality already provided by existing standard artifacts (reinventing the wheel) and ending up with a worse result than the standard (a square wheel). This is an anti-pattern which occurs when the engineer is unaware or contemptuous of the standard solution or does not understand the problem or the standard solution sufficiently to avoid problems overcome by the standard. It is mostly an affliction of inexperienced engineers, or the second-system effect. Many problems contain subtleties that were resolved long ago in mainstream engineering (such as the importance of a wheel's rim being smooth). Anyone starting from scratch, ignoring the prior art, will naturally face these problems afresh, and to produce a satisfactory result they will have to spend time developing solutions for them (most likely the same solutions that are already well known). However, when reinventing the wheel is undertaken as a subtask of a bigger engineering project, rather than as a project in its own right hoping to produce a better wheel, the engineer often does not anticipate spending much time on it. The result is that an underdeveloped, poorly performing version of the wheel is used, when using a standard wheel would have been quicker and easier, and would have given better results. Preinventing the wheel involves delaying a task if it is expected to be undertaken later. An example would be, "We don't want to preinvent the wheel" when discussing a solution to a problem when it is known that the solution is being developed elsewhere. It is not necessarily pejorative. Redefining the wheel is the practice of coming up with new and often abstruse ways of describing things when the existing way of describing them was perfectly adequate. See also Anti-pattern Best practice Design around: an alternative invention that is created in order to avoid patent infringement Not invented here Patent thicket Standing on the shoulders of giants, an expression