Software is constantly changing — the moment it is released, it begins to grow obsolete. Users need a constant stream of patches and want new features. At the same time, people hate when an update introduces a breaking change, especially when they were not warned about it.

Forever it has been common practice to use version numbers and codenames to track releases. Many projects have incrementing sequences (MS-DOS 6.2, 6.21, 6.22); others use part of the release date (Ubuntu 18.04, 20.04, 22.04). A few have a more whimsical disposition: TeX, for example, uses a numbering scheme that asymptotically approaches π (the current version is 3.141592653), while Metafont does the same with e. Its current version sits at 2.71828182.