spaces after period
How many spaces follow a period.
Put one space after a period. Typewriters used monospaced type, so typists added a second space to mark the end of the sentence. Word processors and email use proportional type, and one space is enough. Two spaces leave a hole. Do not put two.
Examples
UseThe gate jammed. We waited. (one space)
AvoidThe gate jammed. We waited. (two spaces)