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Four major types of memory cards (from left to right: CompactFlash, Memory Stick, Secure Digital, and xD.

A memory card or flash memory card is a solid-state electronic flash memory data storage device used with digital cameras, handheld and Mobile computers, telephones, music players, video game consoles, and other electronics. They offer high re-record-ability, power-free storage, small form factor, and rugged environmental specifications. There are also non-solid state memory cards that do not use flash memory, and there are different types of flash memory. They are sometimes called "mem-cards" by gamers and/or techies.

Flash cards have been suggested as a possible replacement for the hard disk in Mp3 players, although USB flash memory drives, which work on almost any computer with a USB port, have been filling this role instead.

There are many different types of memory cards and jobs they are used for. Some common places include in digital cameras, in game consoles, in cell phones, and in industrial applications. PC card (PCMCIA) were among first commercial memory card formats (type I cards) to come out in the 1990s, but are now only mainly used in industrial applications and for I/O jobs (using types I/II/III), as a connection standard for devices (such as a modem). Also in 1990s, a number of memory card formats smaller than PC Card came out, including CompactFlash, SmartMedia, and Miniature Card. In other areas, tiny embedded memory cards (SID) were used in cell phones, game consoles started using proprietary memory card formats, and devices like PDAs and digital music players started using removable memory cards.

From the late 1990s into the early 2000s a host of new formats appeared, including SD/MMC, Memory Stick, xD-Picture Card, and a number of variants and smaller cards. The desire for ultra-small cards for cell-phones, PDAs, and compact digital cameras drove a trend toward smaller cards that left the previous generation of "compact" cards looking big. In digital cameras SmartMedia and CompactFlash had been very successful, in 2001 SM alone captured 50% of the digital camera market and CF had a strangle hold on professional digital cameras. By 2005 however, SD/MMC had nearly taken over SmartMedia's spot, though not to the same level and with stiff competition coming from Memory Stick variants, xD, as well as CompactFlash. In industrial fields, even the venerable PC card (PCMCIA) memory cards still manage to maintain a niche, while in cell-phones and PDAs, the memory card market is highly fragmented.

Nowadays, most new PCs have built-in slots for a variety of memory cards; Memory Stick, CompactFlash, SD, etc. Some digital gadgets support more than one memory card to ensure compatibility.

Since many EEPROM devices only allow a finite number of write cycles, some of these cards incorporate wear levelling algorithms to spread the wear and to avoid wearing out specific places which are often written to.

Main article: Comparison of memory cards

Memory cards' physical sizes keep shrinking down while their respective logical size increases. (Compact flash 32MB, SD 128MB, miniSD 1.0GB, microSD 2.0GB

• PCMCIA ATA Type I Flash Memory Card (PC Card ATA Type I) (max 8 GB flash as of 2005)
  • PCMCIA Linear Flash Cards, SRAM cards, etc.
  • PCMCIA Type II, Type III cards
• CompactFlash® Card (Type I), CompactFlash High-Speed
• CompactFlash® Type II, CF+(CF2.0), CF3.0
  • Microdrive (max 6 GB as of 2005)
• MiniCard™ (Miniature Card) (max 64 MB)
• SmartMedia™ Card (SSFDC) (max 128 MB) (3.3 V,5 V)
• xD-Picture Card™, xD-Picture Card Type M
• Memory Stick, MagicGate Memory Stick (max 128 MB); Memory Stick Select, MagicGate Memory Stick Select ("Select" means: 2x128MB with A/B switch)
• SecureMMC™
• Secure Digital (SD™ Card), Secure Digital High-Speed, Secure Digital Plus/Xtra/etc (SD with USB connector)
  • miniSD™ Card
  • microSD™ Card (aka Transflash, T-Flash)
  • SDHC
• MU-Flash (Mu-Card) (Mu-Card Alliance of OMIA)
• C-Flash™
• SIM card (Subscriber Identity Module)
• Smart card (ISO 7810 Card Standard , ISO 7816 Card Standard, etc.)
• UFC (USB FlashCard) [1] (uses USB)
• FISH Universal Transportable Memory Card Standard (uses USB)
• Disk memory cards:
  • Clik! (PocketZip™), (40 MB PocketZip)
  • Floppy disk (LS120, 2-inch, 3.5-inch, etc.)
• Intelligent Stick (iStick, a USB-based flash memory card with MMS)
• SxS™ (S-by-S) memory card, a new memory card specification developed by Sandisk and Sony. SxS complies to the ExpressCard™ industry standard. [2]
• Nexflash Winbond Serial Flash Moduel (SFM) cards, size range 1mb, 2mb and 4mb.

Many video game consoles have used proprietary solid state memory cards to store data, especially since games started being distributed in read-only optical discs. The sizes in parenthesis are those of the official cards.

• Microsoft Xbox line:
  • Xbox Memory Unit (8MB)
  • Xbox 360 Memory Unit (64MB, 256MB and 512MB versions)
• Nintendo line:
  • Nintendo 64 Controller Pak (256 KB, divided in 123 pages)
  • Nintendo GameCube Memory Card (59- (4 Mib/512 KiB), 251- (16 Mib/2 MiB) and 1019-block (64 Mib/8 MiB) versions) This memory is simply a modified SD card.
  • Wii Nintendo GameCube Memory Card compatible (see above) and Secure Digital card compatible
• Sega Dreamcast Visual Memory Unit (VMU) (128 KB divided in 200 blocks)
• Sega Saturn memory unit can hold 20 blocks of save games.
• Sony PlayStation line:
  • PlayStation Memory Card (1 Mb/128 KB divided in 15 blocks)
  • The PocketStation can act as PlayStation Memory Card
  • PlayStation 2 Memory Card (called the Memory Card (8MB)(For PlayStation 2) onscreen)
  • The PlayStation Portable uses Memory Stick Duo.
  • The PlayStation 3 is compatible with CompactFlash, Secure Digital, and Memory Stick PRO.
• GP2X GNU/Linux based portable games console, uses SD/MMC.

Wikimedia Commons has media related to:

Memory card

• Comparison of memory cards
• USB flash drive
• List of digital camera brands

• Details about Flash Memory and Memory Cards
• CARDSPEED - Card Readers and Memory Cards (speed test measurements)
• Memory Card Guide