Serifed type is often used for long copy, like books and magazines. Nowadays, this rule doesn't even really apply. How many websites use serif for main copy? I

Serifed type is often used for long copy, like books and magazines. Nowadays, this rule doesn't even really apply. How many websites use serif for main copy? Is the BBC less legible than the NYTimes? At small sizes it is not necessarily more legible on screen. There is certainly very little science in choosing fonts; there is more to the world than is dreamt of in science, but a few guidelines might be helpful. Here's a typical designer's process in choosing a font: Consider the use - logo, headling or body copy. For headlines you can afford to have personality and be a little less readable, for body copy legibility is the first concern as it is typically smaller and denser. Consider the medium and size - smaller requires less personality, on screens in particular. In print serif still predominates, particularly on cheap paper, on screen the converse is true and you might have to use larger type if you want to use a serif. Consider the context - what do people expect? What message are you sending when using this font? Consider things like branding or corporate guidelines - that might limit your choice. Finally, consider what mood you want to create, what message you want convey, think of a few adjectives which describe your content. Now look for a font which says all that to you when you first see it. Fonts are like clothes for your thoughts, and like clothes, what they say about the person wearing them is a statement of some kind, even if that statement is just: I don't care about appearances (at this point in time, Helvetica/Verdana). So once you've thought about the above, choosing a font should be fairly simple, and is a matter of browsing through font catalogues available on your device (or google web fonts for example). If you're still stuck, limit your choice to the older ones which are generally considered classics (Gill, Helvetica, Futura, Bodoni, Bembo, Garamond) - using just a few of those would be fine for many uses. And don't forget the measure and line spacing as this is the most often overlooked and useful way of increasing legibility and impact (defaults are often too tight - e.g. this site has spacing which is far too tight and a measure far too long).