About this character
U+00A9 COPYRIGHT SIGN is the encircled capital C used in copyright notices. The symbol entered American statutory law in the 1909 Copyright Act, which required works to display "© [year] [owner]" or a variant in order to claim federal protection. The Universal Copyright Convention of 1952 made the symbol the international standard, replacing a Babel of national requirements (the United Kingdom had favoured the word "Copyright" spelled out; France had no notice requirement at all). For most of the 20th century the symbol was a legal necessity: omit it from a published work in a UCC country and you forfeited copyright in that country.
That changed with the Berne Convention Implementation Act of 1988, which took effect in the United States on 1 March 1989. Berne requires copyright protection to be automatic on creation — no notice, no registration, no symbol. The © therefore became legally redundant in every signatory country for works published after that date. It survives as a customary mark of authorship and a warning to would-be infringers, and US registration still confers a few procedural advantages (statutory damages, attorney's fees), but the symbol itself is no longer load-bearing.
U+00A9 is part of the original ASCII-extended ISO 8859-1 character set, which is why it has been encodable in plain text since the 1980s, and why it has the short HTML named entity ©. Designers occasionally confuse it with the visually similar U+24B8 Ⓒ CIRCLED LATIN CAPITAL LETTER C from the Enclosed Alphanumerics block — semantically a different character, and one whose meaning is "the letter C in a circle", not "copyright". Use U+00A9 for copyright notices. Companion characters in the same block are U+00AE ® REGISTERED SIGN for registered trademarks and U+2122 ™ TRADE MARK SIGN for unregistered claims.
From the Unicode data
Its emoji name (CLDR short name) is “copyright”, in the Symbols group, subgroup other-symbol. By default it is shown as a text glyph; follow it with U+FE0F VARIATION SELECTOR-16 to request the colour emoji form (U+00A9 U+FE0F), or with U+FE0E VARIATION SELECTOR-15 to force text style.