Triple bar

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Identical to
Not identical to
Punctuation
apostrophe ( ’ ' )
brackets ( [ ], ( ), { }, ⟨ ⟩ )
colon ( : )
comma ( , ، 、 )
dash ( , –, —, ― )
ellipsis ( …, ..., . . . )
exclamation mark ( ! )
full stop / period ( . )
guillemets ( « » )
hyphen ( )
hyphen-minus ( - )
question mark ( ? )
quotation marks ( ‘ ’, “ ”, ' ', " " )
semicolon ( ; )
slash / stroke / solidus ( /,  ⁄  )
Word dividers
interpunct ( · )
space ( ) ( ) ( )
General typography
ampersand ( & )
asterisk ( * )
at sign ( @ )
backslash ( \ )
bullet ( )
caret ( ^ )
dagger ( †, ‡ )
degree ( ° )
ditto mark ( )
inverted exclamation mark ( ¡ )
inverted question mark ( ¿ )
number sign / pound / hash ( # )
numero sign ( )
obelus ( ÷ )
ordinal indicator ( º, ª )
percent, per mil ( %, ‰ )
basis point ( )
pilcrow ( )
prime ( ′, ″, ‴ )
section sign ( § )
tilde ( ~ )
underscore / understrike ( _ )
vertical bar / broken bar / pipe ( ¦, | )
Intellectual property
copyright symbol ( © )
registered trademark ( ® )
service mark ( )
sound recording copyright ( )
trademark ( )
Currency
currency (generic) ( ¤ )
currency (specific)
( ฿ ¢ $ ƒ £ ¥ )
Uncommon typography
asterism ( )
index / fist ( )
interrobang ( )
irony punctuation ( ؟ )
lozenge ( )
reference mark ( )
tie ( )
Related
diacritical marks
logic symbols
whitespace characters
non-English quotation style ( « », „ ” )
In other scripts
Chinese punctuation
Hebrew punctuation
Japanese punctuation
Korean punctuation

The triple bar, , is a symbol with multiple, context-dependent meanings. It has the appearance of a "=" sign with a third line.

In logic, it has a similar meaning to the if and only if connective, ⇔. However, in some texts ⇔ is used as a symbol in logic formulas, while ≡ is for reasoning about those formulas (as in metalogic).

In mathematics it sometimes used a symbol for congruence (although not the only one). Particularly, in number theory, it has the meaning of modular congruence: a \equiv b \pmod N if N divides ab.

This symbol is also used when it appears in an equation which is a definition of its left-hand side, that is an equation which is not derived but instead defined.

It is also used for "identical equality" of functions; one writes f \equiv g for two functions f, g if we have f(x) = g(x) for all x.

In chemistry, the triple bar can be used to represent a triple bond between atoms. For example, HC≡CH is a common shorthand for acetylene.

The triple bar character in Unicode as codepoint U+2261 identical to (HTML: ≡ ≡). LaTeX \equiv corresponds to the triple bar.