As there is a wide variety of different types of film for film based cameras, a wide variety of storage mediums exist for digital cameras. While older digital cameras usually relied on internal storage, today's modern digital cameras are more focused on the need for memory cards in order to store photos taken by users.
There really are not any major issues for using a memory card to store your digital photos from your camera. Actually, most people prefer to have their photos store onto a removable card rather than have their photos stored in the internals of the camera. The memory cards allow the amateur photographer to easily transport their photos, and print photographs from the cards at almost every major retail outlet.
Really the only thing that concerns digital camera owners is the fact that there are so many different kinds of memory cards available. These memory cards, known as "flash memory" come in a wide variety of different formats. The problem with all these different formats, is that for the most part, they are not compatible with each other.
The first digital camera that relied on the usage of external flash memory (memory cards) to store their digital photographs utilized floppy disks, and the first kind of flash memory, Compact Flash. Floppy disk (which is not flash memory) based digital cameras were bulky, however because floppy disks were so cheap, it kind of evened out the bulk factor. Unfortunately, the photographs taken with floppy disk based cameras were nothing to write home about, and would be an eye sore compared to digital photographs taken with today's digital cameras.
As mentioned above, Compact Flash was the original external flash memory. While the format is still in use today in other electronics, it is pretty rare to find a new digital camera that accepts the usage of Compact Flash cards. Because Compact Flash was first introduced back in 1994, it is loosing its foot hold in the flash memory industry to newcomers with advanced technologies.
xD-Picture cards are another form of flash memory released in mid-2002 for the sole purpose of usage in digital cameras, because of their extremely small size. Very few camera manufacturers support this form of flash memory, and as a result users who hold digital cameras that only take xD memory cards will pay a premium for the memory cards due to the fact that their exists few manufacturers of xD flash cards.
Sony has their own line of flash memory, which is creatively titled "Memory Stick". Sony is the only company that produces digital cameras, as well as other electronics that utilize their Memory Stick protocol, so just as people who have xD memory cards; owners of cameras requiring a Memory Stick will be paying a premium for their memory.
SD, which stands for Secure Digital is perhaps the most used form of flash memory used on the market today. Available in a wide variety of digital cameras manufactured by literally thousands of different companies allows for the ability of cheap SD memory cards, considering there are also several different companies that produce SD memory cards. If you are looking for the cheapest flash memory cards, then you definitely should purchase a digital camera that utilizes SD memory cards.
The above are just the most popular formats of flash memory. Several other types of flash memory have come and gone, and new formats will be continued to be unveiled. It's kind of harsh that all these different flash memory formats exist, especially for customers who purchase the wrong type of memory card for their camera. Hopefully someday there will either be a universal standard for flash memory, or perhaps the different flash memory specifications will be compatible with each other.