Meaning
A capital C inside a circle, the copyright sign. It shows that a creative work, such as a photo, song, text or design, belongs to its author or owner.
It appears in photo credits, watermarks, footers and posts asking others not to repost without permission: “Photos ©️ by me, please ask before sharing” In plain text the same sign can look small and thin, while the emoji version is bolder. It is a notice, not a legal registration in itself.