This seems surprising, but there is a debate on the Internet regarding the number of gaps after the end of the sentence: should I put one or two? For a long time, Microsoft remained indifferent in its Word text editor, but now it intervened and finally set the norm: there should be only one space (which, in principle, is already obvious).
From now on, a double space in Word will stand out as an error, and the editor will prompt the user to replace it with a single space. Microsoft has already begun releasing this update for Word. However, if you insist on two spaces, you can still put them and ignore the editor’s recommendation.
The argument goes back to typewriter times. Then English typesetters were really taught to put two spaces, but only after the period. This is due to the features of the cars: each character – that “M”, that “I” – was the same width. Thus, narrow letters (like the same “I”) turned out to be visually divorced from the others, because small spaces appeared on the left and right. A double space was visually highlighted, and the reader immediately realized that the sentence was over.
With the advent of PCs and text editors, the problem is a thing of the past, but people of the old school who switched to computers from typewriters out of habit put two spaces.