What is microSD? How does it differ from SD or MiniSD or TransFlash or microSD HC? Will my phone accept microSD? What capacities are available? These are questions addressed in this guide.

microSD       microSD HC

MicroSD is the smallest physical form factor approved for Secure Digital cards.

It is about a quarter of the size of an SD card.  It is about a third of the size of a miniSD card. It is exactly the same size as a microSD HC. By placing the microSD into the appropriate adapter it can function as a full size SD card or the MiniSD card. HC microSD cards have a higher capacity than standard micrsoSD. TransFlash is a trade name for microSD.

Available capacities run from 16 megabytes, common in UK phones from 2005 or so up to 2 gigabytes. The 2 gigabyte cards rarely are standard issue with a device. Most frequently seen are 256 megabytes, 512 megsabytes and 1 gigabyte.

Major suppliers of these cards are Kingston, SanDisk, TopRam and pqi. Counterfeits of the Kingston and SanDisk abound, not only with Asian suppliers but also with eBay sellers based in the USA who source from Asia unless they purchase directly from one of the big names.

If you have a Sony-Ericsson device chances are it will not accept microSD. These devices usually use a M2 Micro that is a proprietary form factor for Sony. Nokia, Motorola, LG, Samsung, Blackberry, Palm and other brands all have devices that accept microSD. Check your owner's guide to ensure it does.

The microSD HC has the same form factor as the microSD but with higher capacity. I'd be guessing if I said what the upper limit of this capacity might be. Would 64 gigabyte max it out? I don't know. Already 8 gigabyte chips are available and this format is in its infancy.

There is a special logo to differentiate the microSD HC from the microSD. If your device has that stylized HC after the microSD it will support microSD HC. A quick and easy to read review of the technical aspects of this memory technology is available at the Sandisk web site