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.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, the 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 prior to the general release of the software as a product.

The software in the beta stage is also known as betaware or beta testing stage. A Beta phase generally begins when the software is feature complete but likely to contain a number of known or unknown bugs. The software in the beta phase will generally have many more bugs in it than completed software, speed or 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. Software beta releases can either be public or private, 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 / technology preview (TP), or early access. Since the introduction of Windows 8, Microsoft has called pre-release software a preview rather than beta. All pre-release builds released through the Windows Insider Program launched in 2014 are termed “Insider Preview builds”. “beta” may also indicate something more like a release candidate, or as a form of time-limited demo, or marketing technique.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.

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 verifications / tests. The remaining bugs are considered as acceptable. This release goes to production. Some domains (for example, Linux distributions), have two types of stable releases: normal, or stable releases and long-term support (LTS) releases which are maintained for a longer period of time.