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.
A sparse file: The empty bytes don't need to be saved, thus they can be represented by metadata. In computer science, a sparse file is a type of computer file that attempts to use file system space more efficiently when the file itself is mostly empty. This is achieved by writing brief information (metadata) representing the empty blocks to disk instead of the actual empty space which makes up the block, using less disk space.