A memory card or flash card is an electronic flash memory data storage device used for storing digital information. They are commonly used in many electronic devices, including digital cameras, mobile phones, laptop computers, MP3 players, and video game consoles. They are small, re-recordable, and able to retain data without power.
PC Cards (PCMCIA) were among first commercial memory card formats (type I cards) to come out in the 1990s, but are now mainly used in industrial applications and to connect I/O devices such as modems. In 1990s, a number of memory card formats smaller than PC Card arrived, including CompactFlash, SmartMedia, and Miniature Card. The desire for smaller cards for cell-phones, PDAs, and compact digital cameras drove a trend 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 stranglehold 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, as well as CompactFlash. In industrial fields, even the venerable PC card (PCMCIA) memory cards still manage to maintain a niche, while in mobile phones and PDAs, the memory card market was highly fragmented until 2010 when micro-SD came to dominate new high-end phones and tablet computers.
MEMORY CARD TYPES:
* PCMCIA ATA Type I Flash Memory Card (PC Card ATA Type I)
o PCMCIA Type II, Type III cards
* CompactFlash Card (Type I), CompactFlash High-Speed
* CompactFlash Type II, CF+(CF2.0), CF3.0
* MiniCard (Miniature Card) (max 64 MB (64 MiB))
* 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: 2×128 MB with A/B switch)
* Secure Digital (SD Card), Secure Digital High-Speed, Secure Digital Plus/Xtra/etc (SD
with USB connector)
o miniSD card
o microSD card (aka Transflash, T-Flash)
* MU-Flash (Mu-Card) (Mu-Card Alliance of OMIA)
* SIM card (Subscriber Identity Module)
* Smart card (ISO/IEC 7810, ISO/IEC 7816 card standards, etc.)
* UFC (USB FlashCard)  (uses USB)
* FISH Universal Transportable Memory Card Standard (uses USB)
* Disk memory cards:
o Clik! (PocketZip), (40 MB PocketZip)
o Floppy disk (32MB, LS120 and LS240, 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. 
* Nexflash Winbond Serial Flash Module (SFM) cards, size range 1 mb, 2 mb and 4 mb.
Game consoles originally used proprietary solid-state memory cards to store the game program and, in some cases, save player progress. In newer home consoles, read-only optical discs have replaced these custom memory cards for storing the game program, resulting in the need for separate memory cards specifically made to save player progress. These memory cards have also been largely superseded by hard drive storage, internal memory and generic storage devices/cards. Most portable gaming systems still rely on custom memory cartridges to store program data, due to their low power consumption, smaller physical size and reduced mechanical complexity.