Denise,

The user is working on a vendor record and while they are doing that the phone rings. It is ACME, a customer, with a question. The user doesn't want to tell the customer please wait while I finish my work or discard the current work. They want to bring up the customer form, answer the question, and then return to their vendor work right where they left off. Non-modal (which is different than modeless) forms allow this to happen.