Datatypes is an extensible file format handling system introduced in AmigaOS 3.0 that allows applications to read and write various file formats through a standardized interface. It operates as a plugin architecture where datatype descriptors handle specific formats like images, audio, or text, enabling programs like MultiView to display content without built-in format knowledge. The system uses the datatypes.library and stores class descriptors in SYS:Classes/Datatypes/, allowing users to add support for new formats simply by installing additional datatype files.