A Binary Large Object (BLOB) is a collection of binary data stored as a single entity in a database management system. BLOBs are typically used to store large amounts of data, such as images, audio files, or multimedia content, which cannot be easily represented in traditional text formats. They allow for efficient storage and retrieval of these large files. BLOBs are commonly found in databases like MySQL and PostgreSQL, where they can be manipulated using specific data types designed for handling binary data. By using BLOBs, developers can manage large files alongside structured data, making it easier to build applications that require multimedia content.