Flash memory is the newest type of mass storage used in personal computers and other electronic devices. The term "flash memory" is a bit confusing. It contains the word "memory" which suggests that its somehow related to RAM and can be used in place of RAM. Flash memory and its function in a computer system is not at all similar to RAM and is in fact much more like a hard disk than RAM. The key difference is that flash, unlike RAM, does not lose data when the computer is turned off and is used to store files, just like a hard drive. Flash memory has no moving parts making it much less fragile than hard drives.

Flash memory can take different forms, depending on the intended use. Digital cameras use removable cards containing flash memory to store pictures. If flash memory is soldered onto a board containing a USB plug and enclosed in a small plastic case, its called a flash drive. Its like having a small hard drive you can throw in your pocket or purse. Flash drives are a great way to move files between PCs, much like the floppy disk was used years ago. No software setup is required to use them in a modern PC: just plug it into an open USB port and you're ready to go. Windows will assign a drive letter to it and it will be listed when you click on My Computer.  The disadvantage of flash memory is that its generally slower than hard drives and much more expensive per gigabyte. The good news is that both factors are improving rapidly. Some high-end laptops are already using flash memory in place of a traditional hard disk but they're still expensive.

Below are various forms of flash memory. They all contain flash memory but the physical size and method of connecting to another device varies.

The top row shows SD, Mini SD, and Micro SD cards. SD cards are used in small digital cameras. Mini SD is often used in personal organizers or music players. Micro SD is used in very small devices such as cell phones. Next to the SD cards is a USB flash drive.

The lower left shows a Memory Stick Pro card and an adapter to allow it to be plugged into a device with the older Memory Stick slot. Memory Stick and all of its variations are used on Sony products. The largest card shown in the lower right is a compact flash card. Its the oldest memory card format still in use and offers the largest capacities. Compact flash, often abbreviated as CF, is most often used in professional level digital cameras.