Is double spacing after a period now a thing?

Solution 1:

Until the early twentieth century, guidelines were numerous and often contradictory. Typesetters often used the large ‘em-quad’ space (traditionally the width of a capital ‘M’) after a period, and the smaller ‘en-quad’ (the width of a capital ‘N’) after all other punctuation. The use of particular letter widths as standards was necessary because most printed material used 'proportional spacing', that is, not all letters were the same width. When typewriters arrived in the 1860s, the convention was adapted so that there was one space between words, and two spaces between sentences. Most typewriters have always produced text that is 'monospaced', that is, all characters (and spaces) are the same width. By about 1950, most style guides advised using only one space between sentences. This is still the case today; you can find this in the style guides of The Economist or the Guardian, and the Chicago Manual of Style. To summarise: the width of white space to add after a period is a matter of style.

One space or two after a full stop?