A reindeer looks like a deer with extra-fluffy fur and very wide antlers. Both males and females grow antlers - in fact, reindeer are the only deer where the females have antlers too. Their hooves spread wide when they walk on snow, like built-in snowshoes, so they don't sink in.
Sámi herders don't keep reindeer in fields like cows. The reindeer roam freely across huge areas of forest and mountain, eating whatever they can find. The herders follow the reindeer, moving with them between summer and winter pastures. The same family might travel hundreds of kilometres a year following their herd.
Reindeer have an amazing party trick: their eyes change colour with the seasons. In summer they are golden. In winter they turn blue. The change helps them see better in the long, dark Arctic winter.
The Sámi people have their own language (with lots of different dialects), their own colourful traditional clothes called 'gákti', and their own flag. They live across the north of Sweden, Norway, Finland and a little bit of Russia. There are about 20,000 Sámi people in Sweden today.