What is a single party check?

In regards to check cashing, a single or one party check is a check in which the check writer and beneficiary are the same person. In other Words, if I write a check from my bank account to myself, I am writing a single party check.

Contrast this with a two party check in which one person or company writes a check to a second person or company, or a three party check in which one person or company writes a check to a second person or company and a third party guarantees some part of the check (usually the funds).