This character is a Other Symbol and is commonly used, that is, in no specific script. The character is also known as asexuality, sexless, genderless, engaged and betrothed.
The glyph is not a composition. Its East Asian Width is wide. In bidirectional text it acts as Other Neutral. When changing direction it is not mirrored. The word that U+26AA forms with similar adjacent characters prevents a line break inside it.
The CLDR project calls this character “white circle” for use in screen reading software. It assigns these additional labels, e.g. for search in emoji pickers: circle, geometric.
This character is designated as an emoji. It will be rendered as colorful emoji on conforming platforms. To reduce it to a monochrome character, you can combine it with Variation Selector-15: ⚪︎ See the Emojipedia for more details on this character’s emoji properties.
The Wikipedia has the following information about this codepoint:
Circle symbol may refer to (in ascending order of size, approximately):
˚, ring diacritic
◦, white bullet
∘, function composition
°, degree symbol
º, masculine ordinal indicator
o, music symbol denoting either a diminished triad or diminished seventh chord
o, superscript lowercase letter o
○, white circle Unicode symbol
◌, dotted circle
oοо, lowercase vowel letters in the Latin, Greek (omicron), and Cyrillic alphabets
𐤏, Semitic/Phoenician letter Ayin, the ancestor of the Greek, Latin, Cyrillic etc. letters
OΟО, uppercase vowel letters in the Latin, Greek, and Cyrillic alphabets