Type is defined by the space around it, whether between letters, words, or lines.
Fixed-Pitch vs. Proportional Typewriter fonts are usually fixed pitch. Fixed pitch means that each character, whether it's an 'i' or 'm', takes up the same amount of space. A fixed-pitch font, such as Courier, works well with the simple, mechanical design of a typewriter. Commercially-printed text and all the modern digital type used on computers is generally designed to be proportionally spaced. With proportional spacing, each letter is given just the amount of space it needs to look right and be most legible.