Are file formats requiring plug-ins known as MIME types?

No, file formats requiring plug-ins are not specifically known as MIME types. MIME (Multipurpose internet Mail Extensions) types are a way to specify the nature and format of a file, allowing Web Browsers to understand how to handle different types of content. While some MIME types may indicate formats that require plug-ins (like certain video or audio types), the term "MIME type" itself refers to the broader classification of file types rather than the need for a plug-in.