A software release life cycle is the sum of the phases of development and maturity for a piece of computer software: ranging from its initial development to its eventual release, and including updated versions of the released version to help improve software or fix bugs still present in the software.
The origin of the "alpha/beta" test terminology is IBM. As long ago as the 1950s (and probably earlier), IBM used similar terminology for their hardware development. "A" test was the verification of a new product before public announcement. "B" test was the verification before releasing the product to be manufactured. "C" test was the final test before general availability of the product. As software became a significant part of IBM's offerings, the alpha test terminology was used to denote the pre-announcement test and beta test was used to show product readiness for general availability. Martin Belsky, a manager on some of IBM's earlier software projects claimed to have invented the terminology. IBM dropped the alpha/beta terminology during the 1960s, but by then it had gotten fairly wide notice. The usage of "beta test" to refer to testing done by customers was not done in IBM. Rather, IBM used the term "field test." .
Pre-alpha
Pre-alpha refers to all activities performed during the software project before 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 functionality is complete.
Alpha
The alpha phase of the release life cycle is the first phase to begin 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.
Alpha software can be unstable and could cause crashes or data loss. External availability of alpha software is uncommon in proprietary software. However, open source software, in particular, often have publicly available alpha versions, often distributed as the raw source code of the software. 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.
Beta
Beta, named after the second letter of the Greek alphabet, is the software development phase following alpha. It generally begins when the software is feature complete. Software in the beta phase will generally have many more bugs in it than completed software, as well as speed/performance issues and may still cause crashes or data loss. The focus of beta testing is reducing impacts to users, often incorporating usability testing. The process of delivering a beta version to the users is called beta release and this is typically the first time that the software is available outside of the organization that developed it.
The users of a beta version are called beta testers. They are usually customers or prospective customers of the organization that develops the software, willing to test the software without charge, often receiving the final software free of charge or for a reduced price. 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, prototype, technical preview (TP), or early access. Some software is kept in perpetual beta—where new features and functionality are continually added to the software without establishing a firm "final" release.
Open and closed beta
Developers 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. The testers report any bugs that they find, and sometimes suggest additional features they think should be available in the final version. Examples of a major public beta test are:
In September 2000 a boxed version of Apple's Mac OS X Public Beta operating system was released.
Microsoft's release of community technology previews (CTPs) for "Longhorn" in January 2005.
Open betas serve the dual purpose of demonstrating a product to potential consumers, and testing among an extremely wide user base likely to bring to light obscure errors that a much smaller testing team might not find.
Impact of the World Wide Web
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".
In February 2005 ZDNet published an article about the recent phenomenon of a beta version often staying for years and being used as if it were in production level, disparagingly called "perpetual beta". It noted that Gmail and Google News, for example, had been in beta for a long period of time and were not expected to drop the beta status despite the fact that they were widely used; however, Google News did leave beta in January 2006, followed by Google Apps, including Gmail, in July 2009.
This technique may allow a developer to delay offering full support and responsibility for remaining issues. In the context of Web 2.0, people even talk of perpetual betas to signify that some software is meant to stay in beta state. Also, "beta" is sometimes used to indicate something more like a release candidate, or as a form of time limited demo, or marketing technique.
Release candidate
A release candidate (RC) is a beta version with potential to be a final 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 bug. 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.