Both SD and microSD cards use an SD interface even though they are clearly a different size of form factor and have commiserate pin out differences in their connectors. SD Host Devices have evolved in keeping with card technology, speed improvements and available density increases. Specific SD Host Devices are limited by the maximum capacity of the card. Newer Host Devices are backwards compatible, with the exception of SDHC to SD, meaning they can support their maximum density as well as all the prior available densities. This applies to both SD and microSD Cards. SD stands for “Secure Digital” and was the first host device supporting capacities from 128 MB to 2 GB. SDHC came next and stands for “Secure Digital High Capacity” which supported densities between 2 GB and 32 GB. SDXC followed, which means “Secure Digital Extended Capacity” and could support densities from 32 GB to 2 TB’s. The latest SD host device is SDUC which means “Secure Digital Ultra Capacity” and supports capacities from 2 TB up to 128 TB.