Considering A Hamster As A Pet
The hamster kept as pet most often is the Golden Hamster, also called Syrian Hamster. So-called Teddybear or Black Bear hamsters are also breeds of golden hamsters.
But also four species of smaller hamsters are popular pets, often called dwarf hamsters. These are Roborovski hamster, (Phodopus roborovskii) often called Roborovski, the chinese striped hamster (Cricetulus griseus) and the two subspecies of Phodopus sungorus, the winter white russian dwarf hamster (Phodopus sungorus sungorus) and Campbell's dwarf hamster (Phodopus sungorus campellii).
The care of the dwarf hamsters is similar to that of the golden hamster, but there are differences in feeding and housing needs and temperament. Winter whites and Campell's are fairly popular, in the US the campells more so than the whinter whites, while it's other way round in Europe.
Roborovski and Chinese striped Hamsters are somewhat more difficult to breed and keep, they are usually only available from breeders, and therefore limited to serious rodentia fans.