Secure Digital (SD) Cards

What Are Secure Digital Cards?

Secure Digital Cards use circuit board cards for storing data. They are like thumb drives but without the bulky case, just the circuit card. Many modern day computers including laptops and tables will have an SD slot for reading and writing to SD cards. SD cards have been around since 1999.

SD cards come in all sorts of shapes and sizes and are used in devices like cameras, camcorders, smartphones and even in handheld gaming consoles. The first SD cards are approximately 1 1/4" inches tall by 1" wide. The mini SD cards were about half the size of the original SD cards, but never really caught on, so they are not found on many devices. A micro SD card is approximately 1.5 cm wide by 1 cm tall and fit inside of an adapter that is the size of the original SD card, making very versatile.

SD Speed Classes

SD speed card classes rate how fast a SD card can read and write data. The speed refers to the absolute minimum sustained write speeds. Class 2 has a minimum of 2MB/s, class 4 - 4 MB/s, class 6  - 6MB/s and class 10 - 10 MB/s.

UHS-Ultra High Speed class refers to the minimum sustained writing performance for video recording.