Final answer:
Expanding files are accordion-style folders used to store files temporarily and help in organizing documents with their multiple expanding pockets and tabs.
Step-by-step explanation:
Expanding files are large, accordion-style folders with tabs in which files can be stored temporarily. Ideal for organizing and storing documents, these files typically have multiple pockets that expand as documents are added, making them versatile for maintaining different types of paperwork in a sorted manner. These organizational tools are especially useful for categories like invoices, receipts, or any paperwork that requires short-term but organized storage.