When at work, I often request for a company's logo and am sent a blurred one as opposed to a sharp one. This is because there's sometimes confusion between available computer formats.

The difference in formats...

1 a raster image (composed of pixels) eg tif / bmp / jpg (all bitmap or pixelated files), and

2 a vector image (composed of paths) eg eps

Here's the thing to remember...

If you enlarge a bitmap / pixelated file of, for example, a logo, it will be blurred beyond belief.

However, if you enlarge a vector / line file of the same logo to 50 kms wide (or even 3 billion kms wide) it will still be sharp... as it is based on geometrical formulas to render the file, resulting in line.

Use whichever suits your needs best ... eg bitmap for web that's low resolution, but vector for sign-writers or anyone creating artwork.

[ Of course, it is very difficult showing vector / line online, as computer monitors are pixelation-based anyway :D ]