Software release life cycle

Pre-alpha refers to all activities performed during the software project before formal testing. These activities can include requirements analysis, software design, software development, and unit testing. In typical open source development, there are several types of pre-alpha versions. Milestone versions include specific sets of functions and are released as soon as the feature is complete.

The alpha phase of the release life cycle is the first phase of software testing (alpha is the first letter of the Greek alphabet, used as the number 1). In this phase, developers generally test the software using white-box techniques. Additional validation is then performed using black-box or gray-box techniques, by another testing team. Moving to black-box testing inside the organization is known as alpha release.[1][2]

Alpha software is not thoroughly tested by the developer before it is released to customers. Alpha software may contain serious errors, and any resulting instability could cause crashes or data loss.[3] Alpha software may not contain all of the features that are planned for the final version.[4] In general, external availability of alpha software is uncommon in proprietary software, while open source software often has publicly available alpha versions. The alpha phase usually ends with a feature freeze, indicating that no more features will be added to the software. At this time, the software is said to be feature complete. A beta test is carried out following acceptance testing at the supplier's site (alpha test) and immediately before the general release of the software as a product.[5]

In general an alpha version or release of a software package intends to do something particular, mostly does so, yet isn't guaranteed to do so fully.

A feature complete (FC) version of a piece of software has all of its planned or primary features implemented but is not yet final due to bugs, performance or stability issues.[6] This occurs at the end of alpha testing of development.

Usually a feature complete software still has to undergo beta testing and bug fixing, as well as performance or stability enhancing before it can go to release candidate, and finally gold status.

Beta, named after the second letter of the Greek alphabet, is the software development phase following alpha. Software in the beta stage is also known as beta ware.[7] A beta phase generally begins when the software is feature complete but likely to contain several known or unknown bugs.[8] Software in the beta phase will generally have many more bugs in it than completed software and speed or performance issues, and may still cause crashes or data loss. The focus of beta testing is reducing impacts on users, often incorporating usability testing. The process of delivering a beta version to the users is called beta release and is typically the first time that the software is available outside of the organization that developed it. Software beta releases can be either open or closed, depending on whether they are openly available or only available to a limited audience. Beta version software is often useful for demonstrations and previews within an organization and to prospective customers. Some developers refer to this stage as a preview, preview release, prototype, technical preview or technology preview (TP),[9] or early access.

Beta testers are people who actively report issues with beta software. They are usually customers or representatives of prospective customers of the organization that develops the software. Beta testers tend to volunteer their services free of charge but often receive versions of the product they test, discounts on the release version, or other incentives.[10][11]

Some software is kept in so-called perpetual beta, where new features are continually added to the software without establishing a final "stable" release. As the Internet has facilitated rapid and inexpensive distribution of software, companies have begun to take a looser approach to use of the word beta.[12]

Developers may release either a closed beta, or an open beta; closed beta versions are released to a restricted group of individuals for a user test by invitation, while open beta testers are from a larger group, or anyone interested. Private beta could be suitable for the software that is capable of delivering value, but is not ready to be used by everyone either due to scaling issues, lack of documentation or still missing vital features. The testers report any bugs that they find, and sometimes suggest additional features they think should be available in the final version.

Open betas serve the dual purpose of demonstrating a product to potential consumers, and testing among a wide user base likely to bring to light obscure errors that a much smaller testing team might not find.

A release candidate (RC), also known as "going silver", is a beta version with potential to be a stable product, which is ready to release unless significant bugs emerge. In this stage of product stabilization, all product features have been designed, coded and tested through one or more beta cycles with no known showstopper-class bugs. A release is called code complete when the development team agrees that no entirely new source code will be added to this release. There could still be source code changes to fix defects, changes to documentation and data files, and peripheral code for test cases or utilities. Beta testers, if privately selected, will often be credited for using the release candidate as though it were a finished product. Beta testing is conducted in a client's or customer's location and to test the software from a user's perspective.

Also called production release, the stable release is the last release candidate (RC) which has passed all stages of verification and tests. The remaining bugs are considered as acceptable. This release goes to production.

Some software products (e.g. Linux distributions) also have long term support (LTS) releases which are based on full releases that have already been tried and tested, and receive only security updates. This allows developers to allocate more time toward product development instead of updating code or finding and fixing newly introduced bugs due to outdated assumptions about the used system, language or underlying libraries.

The term release to manufacturing (RTM), also known as "going gold", is a term used when a software product is ready to be delivered. This build may be digitally signed, allowing the end user to verify the integrity and authenticity of the software purchase. A copy of the RTM build known as the "gold master" or GM[13][14] is sent for mass duplication or disc replication if applicable. This terminology is taken from the audio record making industry, specifically the process of mastering. RTM precedes general availability (GA) when the product is released to the public. A golden master build (GM) is typically the final build of a piece of software in the beta stages for developers. Typically, for iOS, it is the final build before a major release, however, there have been a few exceptions.

It is typically used in certain retail mass-production software contexts—as opposed to a specialized software production or project in a commercial or government production and distribution—where the software is sold as part of a bundle in a related computer hardware sale and typically where the software and related hardware is ultimately to be available and sold on mass/public basis at retail stores to indicate that the software has met a defined quality level and is ready for mass retail distribution. RTM could also mean in other contexts that the software has been delivered or released to a client or customer for installation or distribution to the related hardware end user computers or machines. The term does not define the delivery mechanism or volume; it only states that the quality is sufficient for mass distribution. The deliverable from the engineering organization is frequently in the form of a golden master media used for duplication or to produce the image for the web.

Milestones in a product life cycle: general availability (GA), end of life announcement (EOLA), last order date (LOD), and end-of-life (EOL)

General availability (GA) is the marketing stage at which all necessary commercialization activities have been completed and a software product is available for purchase, depending, however, on language, region, electronic vs. media availability.[15] Commercialization activities could include security and compliance tests, as well as localization and worldwide availability. The time between RTM and GA can be from a week to months in some cases before a generally available release can be declared because of the time needed to complete all commercialization activities required by GA. At this stage, the software has "gone live".

Release to the Web (RTW) or Web release is a means of software delivery that utilizes the Internet for distribution. No physical media are produced in this type of release mechanism by the manufacturer. Web releases are becoming more common as Internet usage grows.

When software is no longer sold or supported, the product is said to have reached end-of-life, to be discontinued, retired, deprecated, abandoned, or obsolete, but user loyalty may continue its existence for some time, even long after its platform is obsolete—e.g., the Atari ST and Sinclair ZX Spectrum.

After the end-of-life date, the developer will usually not implement any new features, fix existing defects, bugs or vulnerabilities (whether known before that date or not) or provide any support for the product. If the developer wishes, they may release the source code, so the platform will live again, and be maintained by volunteers, and if not, it may be reverse-engineered later when it becomes abandonware.