Meaning
A round yellow face with a wide, open grin that shows the top row of teeth, usually with simple oval eyes. It is the plain, all-purpose happy face: friendly, upbeat and easy to read, without the extra intensity of laughing or blushing.
Drop it into greetings, good news or a quick reply to keep the tone warm, as in “Got the tickets 😀 see you Saturday!” Because the eyes stay open and neutral, some people find it a little stiff or forced next to a real laugh, so for something truly funny a laughing face fits better.