Photos have to be "hi-res" or high resolution when printed. A high resolution photo really needs to be at least 300 dpi (dots per inch). This is a bit misleading, in that it's not really dots any more, but pixels, but the term is from the old days… Anyway, many pictures that are digitally sent through email and posted on websites and Facebook are much, MUCH lower in resolution than the 300 dpi that works well in print. A resolution of 72 dpi looks fine on a computer screen, or even in a Powerpoint presentation, but will be very blurry when printed. Here is an example:

If I had found this picture on a website, and copied it (LEGALLY) for use in print media, chances are it would have been 72 dpi. So, let's look at how that would look up close: