Period Mark (.)

In punctuation, the full stop (Commonwealth English) or period (American English) is a punctuation mark placed at the end of a sentence. The full stop glyph is sometimes called a baseline dot because, typographically, it is a dot on the baseline.

One of the most common punctuation marks

The period mark looks like this “.”. It signifies the end of a sentence or phrase. In British English, the period mark is called the “full stop.” Typographically, the glyph is called a “baseline dot” because it is a dot on the baseline; this makes it different from the interpunct (a raised dot, middle dot, middot, or centered dot).

The period mark can also be used after an initial letter, or in mathematics and computing contexts as a “dot” or “point.” The period mark is derived from punctuation started by Aristophanes in the 3rd century B.C.E. Other uses of the dot were noted, but these eventually fell out of use and the period mark became dominant.

The period mark can also be used after an initial letter, or in mathematics and computing contexts as a “dot” or “point.” The period mark is derived from punctuation started by Aristophanes in the 3rd century B.C.E. Other uses of the dot were noted, but these eventually fell out of use and the period mark became dominant.

Learning how to use a period mark

When a sentence ends with a question mark or an exclamation point, the period mark is omitted.

“Did you let the dog out?”

If a sentence ends with an abbreviation, the period mark used for the last abbreviation letter is also the period ending the sentence.

“The dog is currently A.W.O.L.”

An indirect question always ends with a period mark, and not a question mark.

“I wonder if the dog is in the neighbor’s backyard.”

A sentence ending with a parenthetical which is part of a larger sentence requires the period mark to be placed outside the closing parenthesis.

“The dog often wanders over to the empty field on Benton (on the other side of the neighbor’s house).”

If the parenthetical is a sentence on its own, the period is placed inside the parenthesis.

“The dog often wanders over to the empty field. (The field is on the other side of the neighbor’s house.)”

If quoted material ends the sentence, the period mark is placed inside the closing quotation mark, even if it is not part of the original quotation. For example: I found the dog in the neighbor’s yard, and he said, “Woof.”

If the quoted material ends with a question mark or an exclamation mark, the period is omitted. For example: When I asked about the dog, you said, “Have you looked in the neighbor’s yard?”

In abbreviations where the period mark is used as the last period after an abbreviation, such as “He is a D.D.S.”, it also serves as the ending punctuation of the sentence.

Finally, the period mark generally has only one space after it following the end of a sentence, and can also be used in a sequence of three period marks, like this: “…” to form an ellipsis.

Period mark usage in Ancient Greece

In Aristophanes of Byzantium’s time (3rd century B.C.E.), the period mark was used in various ways. A completed though, or expression was followed by a “high dot,” which was called the stigme teleía or “terminal dot.” The stigme mésē or “middle dot” was used as a division between a thought which needed a longer breath (think of the semicolon we use today) and the low dot called the hypostigme or “underdot.”

As of the 9th century B.C.E., the period mark began to appear in the low dot position; the advent of the printing press in Western Europe solidified its position as the universal period mark or full stop.

The period mark first became referred to by this name in the Latin peridos in Ælfric of Eynsham’s Old English grammar treatment. In this writing, it differed from the distinction or English full stop and functioned as the coma between phrases.

In the 16th century, the period came into regular use as the period mark we know today, and by the 19th century both British English and American English used period and full stop interchangeably. The word period was also used by printers to refer to the “full point” or the punctuation mark that was a dot on the baseline and was subsequently used in different situations by the printers. In the 20th century, British English supported “full stop,” while American English kept the “period” terminology.