What severity levels do you know?

There are several commonly accepted levels of defect severity:

1. Blocker: The defect blocks further work with the main functionality or the entire system, with no workarounds available. For example, the application does not start, or login is impossible.
2. Critical: The defect causes the complete non-functionality of a key feature but does not block the entire system. Workarounds are usually unavailable or very complex. For example, it is impossible to place an order in an online store, or a critical report is not sent.
3. Major: The defect disrupts important but not critical functionality, or significantly worsens the user experience. Workarounds may be available. For example, incorrect data display in a report, search by certain parameters not working.
4. Minor: The defect affects non-essential functionality, causes minor inconveniences, or is cosmetic. Simple workarounds are available or not required. For example, formatting errors, minor interface alignment issues.
5. Trivial: The defect is minor, does not affect functionality or data, and fixing it is not a priority. Usually, these are grammatical errors or invisible code issues (unless they are technical debt).

Classification may vary depending on the project, company, and development methodology used. It is also important to consider priority — the urgency of fixing the defect, which may not coincide with severity.