Meaning
A solid blue circle, one of the oldest coloured dots in the emoji set alongside 🔴. It stands for the colour blue and is often read as calm, cool or informational.
It marks the blue side in team games, votes and match-ups, and works as a calm bullet point or a gender-reveal hint: “Vote now: 🔴 beach trip or 🔵 mountain trip” It also suits sea, sky and cold-weather themes. For a square version, 🟦 is the match.