Alpha, Beta, Snapshot, Release, Nightly, Milestone, Release Candidate(RC)... When to use which terminology

Question

As a build, release and deployment engineer, there are multiple types of releases as below:

• Alpha
• Beta
• Snapshot
• Release
• Nightly
• Milestone
• Release Candidate(RC)
• [Anything else]

Would like to know the difference between them and the significance.

Answer 1

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. Alpha software may not contain all of the features that are planned for the final version. 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.

Beta
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 betaware. The beta phase generally begins when the software is feature complete but likely to contain a number of known or unknown bugs. 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. 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/technology 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.

Beta testers are people who actively report issues of 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.

As the Internet has facilitated the rapid and inexpensive distribution of software, companies have begun to take a looser approach to the 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 at the 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 a 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. Since the introduction of Windows 8, Microsoft has no longer been naming its software as a beta. Instead, they have been using the term preview for most pre-release software. Since the launch of the Windows Insider Program back in 2014, all pre-release builds that are released through the program are known as Insider Preview builds.

Snapshot and Release
A snapshot version in Maven is one that has not been released.

The idea is that before a 1.0 release (or any other release) is done, there exists a 1.0-SNAPSHOT. That version is what might become 1.0. It's basically "1.0 under development". This might be close to a real 1.0 release, or pretty far (right after the 0.9 release, for example).

The difference between a "real" version and a snapshot version is that snapshots might get updates. That means that downloading 1.0-SNAPSHOT today might give a different file than downloading it yesterday or tomorrow.

Usually, snapshot dependencies should only exist during development and no released version (i.e. no non-snapshot) should have a dependency on a snapshot version.

Nightly
A nightly build is a neutral build that takes place automatically. These typically take place when no one is likely to be working in the office so that there are no changes to the source code during the build.

Nightly builds are a good thing, they provide immediate feedback to developers if they broke the build. Having a nightly build means that the software is stable and is likely to build for new users. Software that is not built regularly is difficult to release.

Milestone
Milestone versions include specific sets of functions and are released as soon as the functionality is complete.

Release Candidate [RC]
Release candidate. A release candidate (RC), also known as "going silver", is a beta version with the potential to be a final product, which is ready to release unless significant bugs emerge.

Release Candidate (RC) is the build released internally to check if any critical problems have gone undetected into the code during the previous development period. Release candidates are NOT for production deployment, but they are for testing purposes only.