The ability to store data on numerous electronic devices is typically provided by a Secure Digital card. It is commonly known as an SD card, and there are several speeds available. Not everyone needs extreme speeds to enjoy their electronics, but you should have an idea of how high speeds can help before you make a decision.
Many people only consider the amount of space available on their card, forgetting about SD card speed. High speed can allow for devices like cameras to save data faster, as well as to ensure that the images or videos that are saved are high quality. For those who want to save money and do not plan to do things in quick succession, such as take several pictures rapidly, an average SD card speed should be fine. On the other hand, many professionals might find that speed helps them enormously when it comes to doing their job.
Speed grades of SD cards are measured similarly to the speed of CD-ROMs. Since the average CD has a speed of 150 kB/s, SD cards are usually compared to this number in terms of how many times faster they are. The average SD card speed is about six times that of most CD-ROMs, at about 900 kB/s. Some of the best cards have speeds of about 200x, or 30 MB/s, but in most cases 50x should suffice.
One helpful invention by the SD Association includes SD Speed Class Ratings, which can help finding the card you need a bit easier. The three classes are quite intuitive so that they can be remembered by most consumers. Class 2 transfers data at 2 MB/s, while Class 4 transfers it at 4 MB/s. Predictably, Class 6 can send data at 6 MB/s, or 40x the speed of a CD-ROM. The class logo is typically on the package so that the correct SD card speed is easily found at any store.
You should keep in mind which speed is listed when considering SD card speed. Some companies put the write speed on the package, and others record the read speed. In most cases, you can expect the maximum write speed to be the higher of the two types. While the instruction manual of most cameras should specify, be aware that some cameras do require particularly high write speed in order to record smooth videos. Taking numerous pictures within a short time span also sometimes demands a higher write speed, which is why professional photographers often put a lot of consideration into the speed of the SD card before buying.