Logos created for the internet will most likely be very colorful and done using the rgb mode (pixels of red, green and blue). A very colorful rgb logo won’t transfer over to printed materials well because while full-color printing is attractive and popular, it’s also very expensive. And the printing industry uses either “spot colors” or cmyk (cyan, magenta, yellow and black). So if you have a logo designed by a website designer or developer, chances are a graphic designer is going to have to re-create the logo when you go to have something printed. It’s best to start with a good vector logo that will provide you with a a quality file, a flexible size, and consistent colors.
(Note: A vector file will end in .eps)