The term 'Push for Payment' can be summarized as a process of dunning, which is the practice of sending reminders to customers who have not paid their bills. Dunning is typically done by sending letters or emails to customers, and may also involve phone calls or other forms of communication. The term 'DUN' is an acronym for 'Demand for Unpaid Negotiable Instruments, ' which is a legal term used to describe the process of dunning.