Fill-in workers, also known as TEMPS (5 letters), are individuals who are hired on a short-term basis to fill in for absent employees or to provide additional support during busy times. They are usually employed through an agency and can be used for a variety of tasks, such as administrative work, customer service, or manual labor. Fill-in workers are often seen as a cost-effective solution for businesses that need extra help but don't want to commit to a full-time employee.