The term full stop is rarely used by speakers in Canada. It is by far the more common term used in the correct use of English British English. If it is used in Canada, it may be generally differentiated from period in contexts where both might be used: a full stop is specifically a delimiting piece of punctuation that represents the end of a sentence. When a distinction is made, a period is then any appropriately sized and placed dot in English language text, including use in abbreviations (such as U.S.) and at the ends of sentences, but excluding certain special uses of dots at the bottom of a line of text, such as ellipses.
The term STOP was used in telegrams in place of the period. The end of a sentence would be marked by STOP, as punctuation cost extra. The end of the entire telegram would be noted by FULL STOP.
A full stop is used after some abbreviations.
In this use, the full stop is also occasionally known as a suspension mark. This originates from the old practice of marking the end of an abbreviation with the final letter superscript and a dot beneath it (though still "suspended" above where a full stop (period) would go. Another use of the suspension mark is still seen on occasion regarding the c in Mc in logos such as Rand McNally's.
The same glyph has two separate uses with regard to numbers, the one applied being determined by the country it is used in: as a decimal separator and in presenting large numbers in a more readable form. In most English-speaking countries, the full stop has the former usage while a comma or a space is used for the latter:
In countries that use the comma as a decimal separator, the full stop is sometimes found as a multiplication sign, for example: 5,2 . 2 = 10,4. This usage is impossible in countries that use the full stop as a decimal separator, hence the use of the interpunct: 5.2 · 2 = 10.4.. It is still fairly common to use this notation when multiplying units in science, for example 50 km/h would be written as 50 km.h-1, even in countries using a full stop as a decimal separator.
The traditional convention in American English is for full stops to be included inside the quotation marks, even if they are not part of the quoted sentence, while the British style shows clearly whether or not the punctuation is part of the quoted phrase. The American rule is derived from typesetting while the British rule is grammatical (see below for more explanation). Although the terms American style and British style are used it is not as clear cut as that because at least one major British newspaper prefers typesetters' quotation (punctuation inside) and BBC News uses both styles, while scientific and technical publications, even in the U.S., almost universally use logical quotation (punctuation outside unless part of the source material), due to its precision.
As with many such differences, the American rule follows an older British standard. The typesetter’s rule was standard in early 19th century Britain; the grammatical rule was advocated by the extremely influential book The King’s English, by Fowler and Fowler.
In British style, both single and double quotation marks are possible, but more modern style guides like the BBC’s tend to prefer the latter.
Before the advent of mechanical type, the order of quotation marks with full stops and commas was not given much consideration. The printing press required that the easily damaged smallest pieces of type for the comma and full stop be protected behind the more robust quotation marks. The U.S. style still adheres to this older tradition in formal writing but usually not in everyday use. Today, most areas of publication conform to one of the two standards above. However, in subjects such as chemistry and software documentation it is conventional to include only the precise quoted text within the quotation marks. This avoids ambiguity with regard to whether a punctuation mark belongs to the quotation:
References: Chicago Manual of Style, 15th edition; Hart’s Rules for Compositors and Readers at the University Press, Oxford.
There are three main conventions relating to the number of spaces used to separate sentences within the same paragraph:
Note that the term double spacing can also refer to a style of leading: the insertion of a full additional empty line between lines of text. This is commonly used for text which may incorporate later markup or modifications, such as proof-readers' copies or legal documents.
In some Asian languages, notably Chinese and Japanese, a small circle is used instead of a solid dot: "。" (U+3002 "Ideographic Full Stop"). Unlike the Western full stop, this is often used to separate consecutive sentences, rather than to finish every sentence; it is frequently left out where a sentence stands alone, or where text is terminated by a quotation mark instead.
In the Devanagari script used to write Hindi, Sanskrit and some other Indian languages a vertical line (“।”) (U+0964 “Devanagari Danda”) is used to mark the end of a sentence. In Hindi it is known as poorna viraam (full stop). Some Indian languages also use the full-stop such as Marathi.
In Thai, no symbol corresponding to full stop is used as sentence marker. A sentence is written without spaces and a space is typically used to mark the end of a clause or sentence.
In computer programming, the full stop corresponds to Unicode and ASCII character 46, or 0x2E. It is used in many programming languages as an important part of the syntax. C uses it as a means of accessing a member of a struct, and this syntax was inherited by C++ as a means of accessing a member of a class or object. Java and Python also follow this convention. Pascal uses it both as a mean of accessing a member of a record set (the equivalent of struct in C), a member of an object and after the end construct which defines the body of the application.
In file systems, the full stop is commonly used to separate the extension of a file name from the name of the file. RISC OS uses full stops to separate levels of the hierarchical file system when writing path names - similar to / in Unix-based systems and in MS-DOS-based systems.
In Unix-like operating systems, some applications treat files or directories that start with a "." as hidden, meaning, they are not displayed or listed to the user by default.