It’s pretty much a given that programmers look at the computer screen all day at thousands of tiny lines of code looking for that one misplaced semicolon, parenthesis, or curly brace. How do we do it? We cheat.. a little anyways.
Most people don’t give fonts much notice. They can be enormously helpful in making the letters easier to read and making inconsistencies in blocks of text apparent. The first thing I do with an new development environment is copy my font, usually Andale Mono, and shrink the size one or two points.
One thing to point out for non-programmers. We use fixed width fonts on code. That way all the letters line up in a grid. Almost all the fonts in Word are variable width fonts. w and m are wider the 0 and l. The most common fixed width font is Courier New.
Jeff Atwood at Coding Horror has a recent article on programming fonts.