This Slate article unpacks why typography states that everyone needs to quit with the two spaces to begin a new sentence. The dreaded double space was an advent for the typewriter age, two spaces were required as the font used was always a monospace font, which meant words l o o k l i k e t h i s . Monospace fonts are exactly as the name describes, uniformly spaced letters. While a wide letter like an M fit in the allowed space comfortably, an I will have a lot of room on either side. Because of this, an extra space was necessary to indicate that a new sentence was beginning. Which is totally reasonable, typewriters.
But we don’t use them now. People put a lot of effort into making sure that the kerning (the spacing allowed between individual letters) is perfect. The computer age has allowed for highly dynamic kerning, some letters interact well with other letters and poorly with some. Take for example “LT”. See that the top of the T hangs over the bottom of the L? Compare that with “LE”. Even though the T should create an awkward space between it and the L, it knows to come closer together to allow for visual consistency.
And when you double space after a full-stop you’re thumbing your nose to all that wonderful innovation.
Plus it looks ugly as all hell.
Sorry if that’s all super nerdy, but really I’m not sorry. Typewriters were a blip on the radar, and they adapted the double space for legibility. Now everyone needs to drop the double space for legibility.
Read aaaaaall about it right here: