A reindeer looks like a deer with very fluffy fur and wide, branching antlers. Both male and female reindeer grow antlers - reindeer are the only deer where this happens. Their hooves spread wide when they walk on snow, like built-in snowshoes, so they don't sink in even in the deepest drifts.
Reindeer in Finland are not kept in fields. They roam freely across huge areas. The Sami herders know each animal in their family's herd - some by name, some by patterns and ear notches. Once or twice a year, the whole herd is rounded up by snowmobile and helicopter, just so the herders can check on them.
Reindeer have an amazing party trick: their eyes change colour with the seasons. In summer, when daylight lasts almost all night, their eyes are golden. In winter, when the sun barely rises, their eyes turn deep blue. The change helps them see better in the long, dark Arctic winter.
On country roads in Lapland, drivers have to be careful: a reindeer might step out of the trees at any moment. Road signs with a reindeer silhouette warn drivers. There is also a free phone app called 'Porokello' (Reindeer Bell) where drivers can report a reindeer sighting, so other drivers know to slow down.