Secure Digital Card

What Does Secure Digital Card Mean?

A Secure Digital card (SD card) is a non-volatile form of flash memory for portable and mobile devices. Because it is not proprietary, SD card usage is widespread. SD cards are located in thousands of consumer electronic device models, including mobile phones, digital cameras, camcorders, tablets and portable audio players.

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Techopedia Explains Secure Digital Card

SD cards come in three compatible sizes, as follows:

  • MicroSD (15 mm × 11 mm)
  • MiniSD (21.5 mm × 20 mm)
  • SD (32 mm × 24 mm)

SD cards provide large-capacity storage in a tiny package with very low power draw, which is crucial because SD cards are often used in battery powered devices. SD cards also provide a broad range of storage capacity – from a paltry 16 MB at inception to the current maximum of approximately 32 GB. However, the next generation of SD cards, known as SD eXtended Capacity (SDXC), holds up to 2 TB (2000 GB) of data. SD data transfer speeds range from 2 MBps to approximately 90 MBps. By default, SD cards use the File Allocation Table (FAT) family of file systems (FAT16, FAT32, exFAT).

A key SD card feature is that it may be transferred between compatible devices. For example, vacation photos may be transferred from a digital camera to a PC. After inserting the camera’s micro-SD card into the PC’s corresponding slot or adapter, the PC recognizes the card as a new drive.

The SD format is governed by the SD Association – a global consortium of manufacturers.

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Margaret Rouse

Margaret Rouse is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical, business audience. Over the past twenty years her explanations have appeared on TechTarget websites and she's been cited as an authority in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine and Discovery Magazine.Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages. If you have a suggestion for a new definition or how to improve a technical explanation, please email Margaret or contact her…