A more thorough explanation:

A default is when someone fails to do something they were supposed to do. This usually happens when someone owes money to someone else, like a bank or a landlord. For example, if someone doesn't pay their rent on time, they are in default. This means the landlord can take legal action to get the money they are owed.

Another example of default is when someone doesn't show up to court when they are supposed to. This is called a default judgment, and it means the other side automatically wins the case because the person who didn't show up didn't defend themselves.

Overall, default is a serious thing that can have legal consequences. It's important to always fulfill your obligations and do what you're supposed to do.