A type of removable data storage
SD Size Variations
Standard
Stores from 4MB-4GB
Secure Digital High Capacity (SDHC)
Storage capacity of 4GB-32GB
Secure Digital Extended Capacity
Storage capacity of 32GB-2TB
SD Speed Ratings
Speed Class
Can come in 2MB/s, 4MB/s, 6MB/s, 8MB/s or 10MB/s
Ultra High Speed Class (UHS)
Can read and write at a minimum of 30 MB/s
Video Speed Class
Supports video standards like 4K and 8K. The lowest version V6 supports 6 MB/s, but the highest version V90 supports 90 MB/s
Application Performance Class
Video card standard IOPS
A1
1500 IOPS reading 500 IOPS writing
A2
4000 IOPS readin 2000 IOPS writing