They're a hybrid of mandarin and sweet orange and very similar to other mandarins like tangerines, satsumas, and Ojai Pixies.
Clementines are among the smallest orange varieties, almost perfectly round, and typically seedless.
Add to that their honey-sweet taste and a thin skin that makes them easy to peel and separate into segments, and you have the perfect snack for children.
It's no wonder that they're most often marketed in the U.S. as "Cuties" or "Sweeties" ("Halo" and "Darling" are other commercial names). Clementines are typically inexpensive.
Clementines have long been enjoyed in Europe, too.
Their winter arrival at markets—most often from Spain or Morocco—is heralded with high spirits and good cheer.
It's a tradition to buy and eat these bright, sunny fruits and let their sweet, floral aroma fill the house.
They're also a common edible Christmas gift or centerpiece.
Though Spain and Morocco still grow scads of clementines, most are now grown in China.
There are substantial groves in California and Texas as well.