This character is a Other Symbol and is commonly used, that is, in no specific script.
The glyph is not a composition. It has no designated width in East Asian texts. In bidirectional text it acts as Other Neutral. When changing direction it is not mirrored. The word that U+21AD forms with similar adjacent characters prevents a line break inside it.
The CLDR project calls this character “left right wave arrow” for use in screen reading software. It assigns these additional labels, e.g. for search in emoji pickers: arrow, left, right, wave.
The Wikipedia has the following information about this codepoint:
An arrow is a graphical symbol, such as ← or →, or a pictogram, used to point or indicate direction. In its simplest form, an arrow is a triangle, chevron, or concave kite, usually
affixed to a line segment or rectangle, and in more complex forms a representation of an actual arrow (e.g. ➵ U+27B5). The direction indicated by an arrow is the one along the length of the line or rectangle toward the single pointed end.
Representations
System
Representation (click value to copy)
Nº
8621
UTF-8
E2 86 AD
UTF-16
21 AD
UTF-32
00 00 21 AD
URL-Quoted
%E2%86%AD
HTML hex reference
↭
Wrong windows-1252 Mojibake
â†
HTML named entity
↭
HTML named entity
↭
Encoding: GB18030 (hex bytes)
81 36 C9 33
LATEX
\leftrightsquigarrow
RFC 5137
\u'21AD'
Bash and Zsh inside echo -e
\u21AD
C and C++
\u21AD
C#
\u21AD
CSS
\0021AD
Excel
=UNICHAR(8621)
Go
\u21AD
JavaScript
\u21AD
Modern JavaScript since ES6
\u{21ad}
JSON
\u21AD
Java
\u21AD
Lua
\u{21AD}
Matlab
char(8621)
Perl
"\x{21AD}"
PHP
\u{21ad}
PostgreSQL
U&'\21AD'
PowerShell
`u{21AD}
Python
\u21AD
Ruby
\u{21ad}
Rust
\u{21ad}
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