A File is an entity that can store a physical file and some metadata. It also provides an easy access to its size, mime-type, user-defined tags and description thus allowing easy sorting and searching among stored files. There are several methods of file uploading available: multipart/form-data encoded form, RAW POST (by sending file contents as POST body), fetching from URL (by providing the file URL via 'url' param) Attachment is an entity that is used to link a File to one or multiple objects like Customer, Dispute, Payment, Transaction, Order, Plan, Product, Invoice, Note. That allows to quickly find and use files related to those specific entities.