Due to the metadata-rich nature of the Macintosh Hierarchical File System, transferring Mac OS files to platforms that do not support HFS can be problematic. MacBinary was developed as a means of preserving this structure without sacrificing portability. It combines the data and resource forks and the Finder information of a file into a single document. This document is then suitable for transport via FTP, the World Wide Web, and electronic mail. The documents can also be stored on computers that run operating systems with no HFS support, such as Unix or Windows.

Files encoded with MacBinary, regardless of the version, usually have a .bin or .macbin file extension appended to the ends of their filenames. E-mail programs such as Eudora can extract and decode MacBinary mail messages. Most dedicated FTP programs for the Mac, such as Fetch and Transmit, decode MacBinary files they download.

MacBinary is similar to BinHex, but MacBinary produces binary files as opposed to ASCII text. Thus, MacBinary files take up less disk space than BinHex files, but older applications and servers are more likely to corrupt them.