In the past decade, software vendors have emerged to offer in-memory database systems (IMDSs), which are described as accelerating data management for real-time embedded systems by holding all records in main memory. But is this new? For years, database management systems (DBMSs) have employed caching. Several vendors offer something called “memory tables.” RAM-disks and—more recently—Flash-based solid state drives (SSDs) are available for use with databases. Do IMDSs really add anything unique? In fact, the distinction between these technologies and true in-memory database systems is significant, and can be critical to embedded software project success. This paper explains the key differences, replacing IMDS myths with facts.