The term “default” refers to a “failure to act” and the term “judgment” (often misspelled as judgement) means the “final disposition in a legal proceeding”.
When dealing with credit and debt collection issues, default judgments are typically granted because the debtor fails to act; usually by not paying a debt and then by failing to show up in court.
When you fail to appear in court, the judge usually grants the plaintiff (usually a collector) a default judgment. If you receive a court appearance notice DO NOT ignore it!
The only way to protect yourself is to appear in court and present the judge with your side of the story. Go to court prepared to show the efforts you’ve taken in “good faith” to resolve the issue or, in asking for relief in the case of an expired statute of limitations.