A bitmap (e.g. JPEG, PNG, GIF) is made up of thousands of tiny squares or ‘pixels’. These pixels are all the same size, but can be in a huge range of colours. The amount of pixels shown in an image is called ‘resolution’. When there are lots of pixels and an image looks smooth or photographic, that’s ‘high resolution’. When there are less pixels an image might look blocky or ‘pixelated’.
A vector image is more sophisticated: it uses X and Y coordinates to plot each point on a line or curve. This means that vector images are scalable and can be enlarged to billboard size while maintaining smooth edges.
Where possible, we recommend saving graphic designs, text and line art as ‘vector based’ PDFs. This is possible in applications like Adobe Illustrator, Adobe InDesign and more recent version of Adobe Photoshop.