Skin tone emoji let many people and body-part emoji appear with different skin tones. For example, 👍 Thumbs up can be combined with a skin tone modifier to create a more specific thumbs up emoji.
Technically, most skin tone emoji are sequences. The base emoji is followed by a modifier character, and the platform displays the result as one emoji when it supports that combination.
Skin tone options are commonly used with hands, people, professions and activities. They help people represent themselves more accurately, but they are not available for every emoji.
Skin tone emoji are related to emoji variants because they are alternate forms of a base emoji. They are also part of the wider Unicode emoji system explained in Unicode emoji.