Flash memory is the storage medium for DSLR cameras. Most digital cameras today use either SecureDigital (SD) or CompactFlash (CF) removable flash memory cards. Memory cards are rated by their size (the amount of storage), and speed (the rate at which data can be written to the memory). Larger size cards will hold more photos, and faster cards will be able to store photos quicker.
When purchasing memory for your camera, consider the size and speed of the card, as well as the resolution of your camera, and the environment you will be shooting in. How high is your camera’s resolution? The higher the resolution, the faster and bigger your flash card needs to be in order to maximize the number and speed of photos you can take. How many photos will you be taking? Will you be in a place where you can transfer the photos from the card to a computer? Larger cards enable taking more photos before swapping cards or transferring and wiping the current card.