A heart is used to symbolize the emotion of love. Humans have long associated the feeling of love with the heart. The organ used to pump blood around the body. The symbol for Valentine's Day is a heart. A green heart is generally considered positive in that green is associated with growth and renewal. A love for nature. A green heart can also can be associated with envy, jealousy or possessive love.
Emoji History The emoji code/ image log of changes.
This emoji was part of the proprietary / non-standardized emoji set first introduced by Japanese carriers like Softbank. These emojis became part of the Apple iPhone starting in iOS 2.2 as an unlockable feature on handsets sold in English speaking countries.
In iOS 5 / OSX 10.7, the underlying code that the Apple OS generates for this emoji was changed.