DPI = DOTS PER INCH
On the Web everything you see is 72 DPI. Why you ask? Because the files have to be small enough for you to download them and so your monitor and graphics card can actually display them without crashing your computer.
In Printing everything must be 300 DPI. Why you ask? Because you don’t want your brochures to appear blurry and pixilated. (Pixilation is when you can actually see the dots that make up an image)
