The first digit assigned to all Visa cards is four, and the second through sixth numbers are connected to the financial institution. Then, either the seventh through 12th numbers, or the seventh through 15th, are the account number, while that final 13th or 16th digit is the check number.
Limited color, Lossy format, small file. GIF(Graphics Interchange Format) is limited to an 8-bit palette, or 256 colors. This makes the GIF format suitable for storing graphics with relatively few colors such as simple diagrams, shapes, logos and cartoon style images.
There is an extremely large number of different bitmap formats. Lossy image formats (e.g., JPEG) have smaller file sizes but do not store a perfect copy of the image. They are best suited to photographs and other images where perfect accuracy is not important. They are also commonly used on the web to save bandwidth.