: | ː

The colon (:) is a punctuation mark used in many ways:

• to introduce lists (like this one)
• before a definition
• before a description
• to make explicit or expand on something, as exemplified on the following line:
• in Finnish and Swedish: to indicate possession (playing the role similar to that of the apostrophe in English)
• before an explanation or an example, as shown on the following line
• to form contractions, as in Swedish: Thomas Gustafsson can be abbreviated as Thomas G:son
• before direct speech or quotations. For example, Wikipedia says:

  In British English, it was once common for a colon to be followed by a hyphen or dash to indicate a restful pause, in a typographical construction known as the “dog’s bollocks”, though this usage is now discouraged.

• to introduce spoken words in written dialogues
• to separate a title and subtitle of a work when written the same line
• in American English: in formal letter writing
• to separate hours:minutes:seconds when written in numbers
• to separate chapter:verse in Biblical citations
• in mathematics and elsewhere to indicate a ratio or a scale
• in a variety of other ways in mathematics
• in certain O:B:Sc:U:Re ways in chemical nomenclature
• in many ::wonderful ways:: in C:\omputing

A triangular colon (ː) is used in International Phonetic Alphabet to mark /mɑːk/ the preceding sound as “long”.

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. | 。

The full stop or period (.) is a punctuation mark typically found at the end of a sentence, unless it is a question or exclamation.

In the 3^rd century BC, the Greeks developed a punctuation system where ὑποστιγμή (the low dot .) functioned as the modern comma, while στιγμὴ μέση (the interpunct or the middle dot ·) played the role similar to that of the modern semicolon; στιγμὴ τελεία (the high dot ˙) marked the end of a completed thought, like the modern full stop.

Classical Latin had no lower-case letters, interword spacing or punctuation; hovvever·the·interpvnct·vvas·sometimes·vsed·to·separate·vvords

Apart from the ends of sentences, full stops are found after initials, some abbreviations and acronyms. In English-speaking countries, they indicate a decimal point, although in Britain until 1970s they used the interpunct for this purpose.

In Chinese and Japanese, a small circle 。 is used to indicate the end of sentence instead of a solid dot .

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