Bug Severity and Priority definitions

Severity - an objective, absolute, and technical assessment of the bug:

1. Bug causes system crash and/or data loss.
2. Bug causes major functionality or other severe problems; or product crashes in obscure cases.
3. Bug causes minor functionality problems; or bug relates to wording issues in high visibility areas - impact is on "fit anf finish".
4. Bug contains typos, unclear wording or error messages in low visibility areas.

Priority - a subjective, relative, and "business or consumer" assessment of the bug:

1. Critical: Must fix NOW - bug is blocking further progress in testing.
2. High: Must fix as soon as possible - prior to next build.
3. Medium: Should fix soon, before product release.
4. Low: fix if time; somewhat trivial. May be postponed.

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Johanna Rothman provides another simplified way:
Instead of priority and severity, I use risk as a way to deal with problem reports, and how to know how to fix them. Here are the levels I choose:

• Critical: We have to fix this before we release. We will lose substantial customers or money if we don’t.


• Important: We’d like to fix this before we release. It might perturb some customers, but we don’t think they’ll throw out the product or move to our competitors. If we don’t fix it before we release, we either have to do something to that module or fix it in the next release.


• Minor: We’d like to fix this before we throw out this product.

Here is the full article:
http://www.stickyminds.com/sitewide.asp?Function=edetail&ObjectType=COL&ObjectId=6288