The Secure Digital (SD) memory card format was developed for portable devices across a wide range of product categories and is the unofficial industry standard for memory card format. SDHC is the high capacity variant of the memory card format.

An SD (Secure Digital) card is a portable storage device that stores data even when it is not powered. SD cards are very small and fit in many portable devices such as cameras, video game consoles, and cell phones. They can also be used with both desktop and laptop computers if the user purchases an SD card adapter.

A memory card is any small device that allows for a user to store files of a large variety on it for mobility. In other words, a user can take a memory card, insert it into a computer, put files on it–including text documents, pictures, audio files and video files–and then remove the card and bring it to another computer.

A memory card reader is a device that acts as a connection between a flash memory stick or SD memory card and the computer. In other words, it is a memory hub that makes it possible to connect multiple memory cards to the computer at one time.

A USB flash drive is a small, external hard drive that can hold files, pictures and music depending on the size of the flash drive. It is called a flash drive because it is made up of flash memory which can easily be erased and reprogrammed.

Flash memory is memory which retains its contents even after power is removed.
Flash memory is a form of EAPROM (Electrically Alterable Programmable Read-Only Memory).
Each bit of data in a flash memory device is stored in a transistor called a floating gate. The floating gate can only be accessed though another transistor, the control gate.

The Secure Digital Input/Output card standard expands upon the original Secure Digital card standard, extending the functionality of many devices with SD card slots.
The Secure Digital Input/Output card standard is based on the Secure Digital standard.

NAND drives are high-capacity, high-speed, solid-state flash memory drives. Thanks to new advances in technology, these drives have been chosen to become the latest drive preference for laptop computers (hopefully in the near future). When comparing the NAND to other types of flash memory, NAND drives have several noteworthy advantages.

A SD Card (Secure Digital Card) is an IC (Integrated Circuit) which is stored in a compact and rugged plastic enclosure. SD Cards are designed to store data and to enable the transfer of data between devices equipped with SD Card slots.
Current SD Card capacities range up to 1GB.
A SD Card is 32mm long, 24mm wide, and 2.1mm thick.

A multimedia card, or MMC, is a small, flash-based storage device that allows portable devices to store memory. While SD cards and CompactFlash cards used to be the standard for portable digital devices, multimedia cards are more resilient to damage and are also much smaller.