Parameter optional?
If I set up a query with some of its fields criteria set equal to a form, how can I tell the query that the form is optional (or in other words, that the parameter is optional)

The way to work this depends on what you are looking for on your form.

You can utilize the OR part of the query criteria.....or you could write code (Query Def) to tell a form to open to specific data where you leave search fields blank on your form.

If you're not going for either of those, I would just create the same query without the criteria.