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+25AB forms with similar adjacent characters prevents a line break inside it.
The CLDR project calls this character “white small square” for use in screen reading software. It assigns these additional labels, e.g. for search in emoji pickers: geometric, small, square, white.
This character is designated as an emoji. It will be rendered as monochrome character on conforming platforms. To enable colorful emoji display, you can combine it with Variation Selector-16: ▫️ See the Emojipedia for more details on this character’s emoji properties.
The Wikipedia has the following information about this codepoint:
Geometric Shapes is a Unicode block of 96 symbols at code point range U+25A0–25FF.
Representations
System
Representation (click value to copy)
Nº
9643
UTF-8
E2 96 AB
UTF-16
25 AB
UTF-32
00 00 25 AB
URL-Quoted
%E2%96%AB
HTML hex reference
▫
Wrong windows-1252 Mojibake
â–«
HTML named entity
▫
Encoding: GB18030 (hex bytes)
81 37 9B 35
AGL: Latin-5
uni25AB
Adobe Glyph List
H18551
Adobe Glyph List
whitesmallsquare
RFC 5137
\u'25AB'
Bash and Zsh inside echo -e
\u25AB
C and C++
\u25AB
C#
\u25AB
CSS
\0025AB
Excel
=UNICHAR(9643)
Go
\u25AB
JavaScript
\u25AB
Modern JavaScript since ES6
\u{25ab}
JSON
\u25AB
Java
\u25AB
Lua
\u{25AB}
Matlab
char(9643)
Perl
"\x{25AB}"
PHP
\u{25ab}
PostgreSQL
U&'\25AB'
PowerShell
`u{25AB}
Python
\u25AB
Ruby
\u{25ab}
Rust
\u{25ab}
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