With the introduction of more compact technology Sd cards became the most popular medium of storing data on compact devices. They can be found everywhere taking from mobile phones, tablets, Mp3 players, digital cameras, camcorders, voice recorders and much more. Although their function is same, their specifications are quite different from each other.
Knowing the details:
For a start, SD cards come in three physical sizes. These comprise standard-size SD cards (first developed in 1999), smaller mini SD cards (introduced on some mobile phones in 2003), and the even smaller micro SD cards. The latter was invented in 2005 and are becoming increasingly popular on smartphones and tablets. While the larger cannot fit in smaller card slots, so adapters are available to enable micro and mini SD cards to be accessed by any device that accepts a standard size card.
The SD card comes in three capacity types known as SD, SDHC, and SDXC. The first of these can store up to 2 gigabytes of data. SDHC (SD high capacity) cards are then available in capacities of between 4 and 32 gigabytes, while SDXC (SD extended capacity) cards range from 32 gigabytes up to a theoretical 2 terabyte (although at present only 200 GB cards are on the market (SanDisk)).
Because SD cards now come in three capacity types, not all SD devices can access all SD cards of the same physical design. While standard SD cards can be read by any device, SDHC cards should only be inserted into SDHC or SDXC devices. SDXC cards must then only be used with the latest SDXC hardware. Even if you try to use an SDXC or SDHC card in a device that does not support it then you may suffer from loss of data or even damage the card itself.
SD cards have different classes, different classes have different read and write speed. These classes are known as Class 2, Class 4, Class 6, Class 10, and UHS-1 (ultra high speed 1). Many manufacturers also label cards with multiple that compares them to a CD-ROM drive. Absolute data transfer ratings are sometimes also included. However, in practical terms, it is the speed class that really matters.
The higher SD card’s speed class, the faster it is but the more it will cost. For most purposes class 4 or class 6 cards are fine. Class 10 or UHS-1 are best for high definition video or when otherwise handling large quantities of data. Also, there are UHS-2 cards which are best of 4K recording. Currently, SanDisk is the pioneer in the SD card market, they have all kind of Sd cards.