Swedish meatballs are smaller than the meatballs you might know from Italian pasta dishes. They are also a bit sweeter, because the recipe usually includes a little milk and breadcrumbs mixed in. They are pan-fried in butter so the outsides go brown and crispy.
The classic plate has four things on it: meatballs, mashed potato, gravy, and lingonberry jam. The lingonberry jam is the surprise - a sweet-tangy red jam made from small berries that grow in the Swedish forest. Eating it with savoury meat sounds odd if you've never tried it, but the sweet-and-savoury mix is delicious.
Köttbullar are not just for fancy dinners. Most Swedish schools serve them in school lunch. Every IKEA store - and there are over 400 of them across the world - has a restaurant inside where you can buy köttbullar for not much money. Many people who have never been to Sweden have eaten Swedish meatballs at IKEA.
Lingonberries - the little red berries used for the jam - grow wild all over Sweden's forests. Families pick them in late summer and boil them with sugar to make jam that lasts the whole year. Some Swedes have lingonberry jam at almost every meal.