5/11/09 BIG and small
Upper case and lower case are pretty well-known terms for anyone dealing in type or the written word. You know, CAPITAL LETTERS and non-capital letters. Have you ever wondered where those terms come from, what they refer to? Here's the answer whether you've ever wondered or not.
It all goes back to the big breakthrough in printing, moveable type. Gutenberg's big invention was not the printing press itself, but standardized, individual letters on little metal blocks that could be assembled into any text. This way you could print a Bible or a do-it-yourself book with the same bits by rearranging them without having to start over from scratch.
These letters were stored and organized in wooden cases with a series of partitions making cubby holes for each particular letter. These were standardized so typesetters could find what they needed with all the capitals in the upper part and all the non-capitals in the lower part. Hence upper and lower case.
Now a bit of minutiae you may not have considered. If you've played around with typefaces you may have noticed some fonts look smaller at the same point size compared to other fonts. That's because they are, even though they ain't. Which sounds like gibberish, but I can explain.
Above are the letters "I, x, p" in 80 point type. The first font is Humanist and the second is Helvetica. As you can see, if you set them on the same base line both the upper case and the lower case letters are taller in Helvetica. But point size isn't measured that way. It goes from the bottom of the descender, the tail of the "p" to the top of the ascender, the top of the "I".
When you line them up like that, they are the same size. You will notice the lower case "x" in each are different sizes. This is referred to as the x-height of the font. A typeface with a smaller x-height will look, or read smaller than a font with a bigger x-height even when they're the same point size.
If you're interested, you can read about the another built-in optical illusion of type here.