Selecting a microSD or SD card to design into an application used to be a simple decision-making process. A designer needed only to ensure the NAND architecture met the performance, temperature rating and longevity needs of their project. Then along came form factor differences, UHS speed classes, Video Speed Classes, and Application Performance Classes. These factors along with considerations accounting for Bus Speed, Host Device Compatibility and Capacity Compatibility have made the microSD and SD card landscape confusing. There are so many symbols on a microSD card today, it looks like alphabet soup.