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.
Image file size is measured in KB (kilo bytes) and for web/eBay use you really want to keep this number down while still maintaining good image quality. By default, a high quality JPEG image sized 600 x 400 pixels can be as large as 300KB or more. This is too much, especially if you have loads of images in your listing.ust use whatever size seems right for you when cropping images. If the product image is in portrait format, the height will actually be more than the width so in cases like these, the width will still be 600 pixels but the height could be 800 or even 900 pixels.