Nowadays, memory cards are widely used in our daily lives. People use memory cards in their digital cameras, phones, etc. Because these cards are very slim and small that they can be easily inserted, removed. Moreover, with the advancement of technology, your favorite music collections and pictures can be stored through memory cards. Memory cards are the media for modern data storage and preservation. As long as you have one, you can conveniently keep digital files and share it to your friends.
However, the wide variety of memory card types and makers reflects the relative immaturity of the field of digital photography. The different companies are still battling for market dominance, and no standard has yet been established for memory cards. There are presently two main types of memory card that seem to stand above the others. These two types are known as Compact Flash (or CF) and Secure Digital (SD). For the remainder of this article I shall restrict my discussion to these two card types. Most digital cameras will support only one memory card type, though the very high end digital SLR models, like the Canon EOS-1Ds Mark III and the Nikon D3 support both CF and SD memory cards for maximum flexibility.
While your memory card that is full of images, the most common way to transfer images from your memory card is to use a card reader. This is a small device, roughly of ipod size, which contains one or more memory card slots at one end, and a cable at the other end which connects to the USB port of your computer. In this way, your card reader simply becomes another port from which to read data onto your hard drive.
Eventually, you can buy the memory cards everywhere. The most convenient is buying the cards though the internet. Before you purchase the cards, remember to choose the retailer which you trust.