CompactFlash (CF) was originally a type of data storage device, used in portable electronic devices. As a storage device, it typically uses flash memory in a standardized enclosure, and was first specified and produced by SanDisk Corporation in 1994. These cards contain both memory chips and a controller. Most digital cameras that utilize CompactFlash cards can use any storage size CF card up to around .5 - 1GB with no major issues. CF cards with a storage of 2GB or more, however, use the FAT-32 file system, and some cameras may not be able to read this kind of memory. There are two types of Compact Flash cards - Type I (3.3mm thick) and Type II (5mm thick) CF cards. Digital cameras with Type I slots can't use Type II cards. However, devices with Type II slots can use both. Compact Flash cards have good transfer speeds (up to 20 Mbyte/s write and 20 Mbyte/s read for the SanDisk Extreme III) and available in capacities from about 8 megabytes to about 12 gigabytes.

SD cards are based on the older Multi Media Card (MMC) format, but most (not all) are slightly thicker than MMC cards. These flash memory cards were originally designed to hold copyrighted musical content and prevent its unauthorized duplication. Although this use was not widely adopted, SD cards have become the flash memory of choice for digital cameras because of their small size and low power consumption. Small cameras need small memory cards and the larger CF cards were no longer viable due to their physical size. SD memory cards are physically smaller than SmartMedia cards but thicker. Most (not all) offer an optional lock switch on the side to prevent accidental overwriting, and (little-used) DRM security features. There are two main types available, ones that run at regular speeds, and high-speed cards that have higher data transfer rates. These cards range in size from 4MB up to 2GB. SD cards generally measure 32 mm x 24 mm x 2.1 mm, but can be as thin as 1.4 mm, just like MMC cards. Devices with SD slots can use the thinner MMC cards, but the standard SD cards will not fit into the thinner MMC slots. SD cards can be used directly in CompactFlash or PC Card slots with an adapter. MiniSD and microSD cards can be used directly in SD slots with an adapter. There are some SD cards that have a USB connector built in for dual-purpose use, and there are readers which allow SD cards to be accessed via many connectivity ports such as USB, FireWire, and the common parallel port.

The miniSD Memory Card offers all of the benefits of a standard SD Card, but in a much smaller size. In fact, it is over 60% smaller than a full-sized SD Card. The miniSD Memory Cards are used to store digital images, video, MP3 files and other data in mobile phones. The miniSD Cards usually include an adapter that converts the mini SD Card into a full size SD Card to be used with the growing number of SD compatible devices available in the market.

The microSD format was originally created by SanDisk. It was originally called T-Flash and then TransFlash before being renamed microSD when adopted by the SD Card Association (SDA). The microSD Memory Card offers all of the benefits of a standard SD Card, but in a much smaller size. micro SD cards are 11 mm x 15 mm x 1 mm thick and are intended for use in small devices like mobile phones and portable audio players. microSD cards come in capacities ranging from 16 to 512 megabytes (2 GB expected in 2006).

Memory Stick is a flash memory card format, launched by Sony in October 1998, and is also used in general to describe the whole family of Memory Sticks ("Memory stick" is also occasionally used to refer informally to USB flash memory drives.). This family includes the original Memory Stick, Memory Stick Pro, a revision that allows greater maximum storage capacity and faster file transfer speeds and maximum theoretical capacity of 32 GB, Memory Stick Duo, a small-form-factor version of the Memory Stick, and a Memory Stick PRO Duo. Memory Stick PRO Duo is half the size of a standard-size Memory Stick PRO media and it offers the same technologies including high speed data transfer, built-in MagicGate*, and high capacities. Form Factors:

• Standard: 50.0 mm W x 21.5 mm H x 2.8 mm D
• Duo: 31.0 mm W x 20.0 mm H x 1.6 mm D

The Memory Stick can be used in digital cameras, digital music players, PDAs, cellular phones, the PlayStation Portable, and in other devices. *MagicGate is a copy-protection technology that works by encrypting the content on the device using MagicGate chips in both the storage device and reader to enforce control over how files are copied.

SmartMedia is a flash memory card standard owned by Toshiba. It was launched in the summer of 1995 to compete with CompactFlash format. These memory cards are typically smaller than a lot of the CompactFlash cards. They save space by providing a storage system essentially integrated onto a plastic card, much like a credit card device. SmartMedia cards larger than 128 MB have not been released, and some older devices cannot support cards larger than 32 MB without a firmware update (or at all in some cases). SmartMedia cards come in two formats, 5 V and 3.3 V (sometimes marked 3 V), named for their main supply voltages. The packaging is nearly identical, except for the reversed side of the mechanical orientation notched corner. Size: 45.0 x 37.0 x 0.76 mm, Weight: 2g.

The Multimedia Card (MMC) is a flash memory card standard. MMC is about the size of a postage stamp: 24 mm x 32 mm x 1.5 mm. Multimedia Card (MMC) originally used a 1-bit serial interface, but newer versions of the specification allow transfers of 4 or sometimes even 8 bits at a time. MMC cards can be used in any device which supports SD cards. A 64MB Multi Media Memory Card holds 64 minutes of MP3 or about 40,000 book pages and MMC cards are currently available in sizes up to and including 2 GB. The MultiMedia Memory Flash Card is an ultra-small, high storage solution for MP3 music players, digital video, cellular phones, digital cameras, PDAs and global positioning systems (GPS).

MMC cards also come in a smaller form factor, of about half the size: 24 mm x 16 mm x 1.5 mm. This form factor is known as Reduced-Size Multimedia Card, or RS-MMC, and was introduced in 2004. RS-MMC cards are simply smaller MMC cards; by using a simple mechanical adapter to elongate the card, an RS-MMC card can be used in any MMC (or SD) slot. Reduced-Size MMC (RS-MMC) cards are currently available in sizes up to and including 1 GB.

xD stands for eXtreme Digital. It was developed by Olympus and Fujifilm, who introduced it to the market in July 2002. The Toshiba Corporation manufactures the cards for Olympus and Fujifilm. Other brands, including Kodak, Silicon Power, SanDisk, and Lexar, sell xD picture cards also. xD cards are currently available in these capacities: 16MB, 32MB, 64MB, 128MB, 256MB, 512MB and 1GB (Type M). An xD card is 20mm x 25mm x 1.78mm and weighs 2.8 grams. The 16MB and 32MB models write at 1.3mb/s and read at 5mb/s. The 64MB, 128MB, 256MB and 512MB models write at 3mb/s and read at 5mb/s. The 1GB (Type M xD card) model writes at 2.5mb/s and reads at 4.0mb/s. The Type M was released in 2005. It uses Multi Level Cell (MLC) architecture to achieve higher storage capacity than the 512MB. Although Type M capacity will eventually stretch to 8GB, the 1GB card is currently the only card in this range. The xD format primarily competes with formats such as Secure Digital Card (SD), CompactFlash (CF), and Memory Sticks. xD cards are fast in comparison with formats such as SmartMedia (SM), MultiMediaCard (MMC) and MemorySticks (MS), but xD picture cards are much slower than the main competitor SecureDigital (SD).

Card Readers are high quality devices for transferring your digital images from media storage cards to your computer and are available for CompactFlash , SmartMedia, Memory Stick, SecureDigital cards, miniSD, microSD, T-Flash, TransFlash, xD-Picture Cards, MultiMedia cards (MMC), and Redused Size MMC cards. Card Readers are faster and easier to use to download your images than using a connector cable between your camera and computer. They are virtually plug and play with your computer (drivers may be needed in some cases).