Digital cameras have been using a memory card system for storing photos for quite some time now. The cameras store photos as jpg files (or in another format, depending on the camera), and all that has to be done is to transfer the card's contents to your computer’s hard disk to be able to see a photo, edit it or print it out. At the time when digital cameras came onto the market, the only way to connect them to a computer was through a serial port, an extremely slow process. Currently, digital cameras can be connected to the computer’s USB port, providing a faster file transfer rate.

There are several formats of memory card on the market, seeing that the major digital camera makers, instead of following a single joint standard, opted for setting up individual standards. The most outstanding ones are Compact Flash (CF), Memory Stick (MS), MultiMediaCard (MMC), Secure Digital (SD), SmartMedia (SM) and xD.

In this tutorial we will explain in details the technical differences of each one of the leading memory cards standards, since they are not compatible among them. It is important to notice that the difference is not on the physical side. An important aspect of cards is their transfer rate or speed. With a faster transfer rate you can not only the files faster to your computer but also when shooting pictures the camera can be ready faster for you to take your next snapshot. Since each camera model uses one type of card, the type of memory card the camera uses can be a very important aspect when buying your digital camera. Power consumption can play a relevant role on battery life and is an aspect one should pay also attention.

Capacity is also one of the most important features of a memory card. Keep in mind that with older standards like MultiMediaCard and SmartMedia you won't be able to use high-capacity cards (above 256 MB) because they simply don't exist for these standards. We will be discussing that on our tutorial as well.

Before going ahead, you may want to take a look on the following table. This is a table to help you to choose the memory card size for your camera, based on its resolution, in megapixels. "File size" means the average file size using camera's "high-resolution" JPEG mode. The actual number of images per card will vary and depends on the camera model and complexity of the scene being photographed. The number on each row indicated the number of pictures a given memory card can hold at a given resolution. For exemple, a 128 MB memory card can hold approximately 106 pictures using 3 megapixel resolution.

Approximate Number of Images per Capacity
Camera Type:	File Size	32 MB	64 MB	128 MB	256 MB	512 MB	1 GB	2 GB	4 GB
2 Megapixel Camera:	900KB	35	71	142	284	568	1,137	2,275	4,551
3 Megapixel Camera:	1.2MB	26	53	106	213	426	853	1,706	3,413
4 Megapixel Camera:	2MB	16	32	64	128	256	512	1,024	2,048
5 Megapixel Camera:	2.5MB	12	25	51	102	204	409	819	1,638
6 Megapixel Camera:	3.2MB	10	20	40	80	160	320	640	1,280