What are pre-release versions?

Pre-release versions are preliminary versions of a product that are shipped before the final release, to test changes and gather feedback.

Simply put: it's "almost ready, but not for everyone yet".

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#What pre-release versions look like

In semantic versioning (SemVer), pre-release is marked with a suffix after -:

The general format:

MAJOR.MINOR.PATCH-<pre-release>

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#The most common types

#alpha

• a very early version
• may be unstable
• often without full functionality

1.2.0-alpha

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#beta

• functionality is largely complete
• bugs are possible
• used for testing

1.2.0-beta

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#rc (release candidate)

• a candidate for release
• if no bugs are found, it becomes the final version

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#How pre-release differs from a regular release

• is not considered stable
• can change or be removed
• is meant for testing, not for production
• the final version is released without the suffix

1.2.0-rc.3 → 1.2.0

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#Pre-release and Git / tags

Usually:

• pre-release versions are marked with tags
• CI/CD can:
  • deploy them to staging
  • not deploy them to production
• production is often configured only for tags without suffixes

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#Why pre-release versions are needed

#Early testing

• finds bugs before the release
• checks integrations

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#Feedback

• users or QA try out the new version
• behavior can be adjusted

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#Release safety

• production does not break
• risks are moved into test environments

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#An important SemVer nuance

According to SemVer rules:

• 1.2.0-beta is lower than 1.2.0
• pre-release versions are not recommended for production

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#Short answer for an interview

Pre-release versions are preliminary versions of a product (alpha, beta, rc) that are shipped before the final release for testing and verification, and are marked with suffixes in SemVer.