Giants have been in Nordic mythology for a long time. According to Old Norse mythology, giants were the enemies of Gods and humans. Most giants came from Jotunheim, located at the very top of the world. According to Old Norse beliefs, the whole world was built from a giant named Ymer. For example his flesh is the earth, his blood the water, his teeth the mountains and his hair the woods.
From mythology, giants are a tall family that lived on earth long before mankind. There are different sizes of giants. Everything from just "big" to gigantic creatures that totally remodeled the Nordic landscape. One story tells that an enormous giant took a handful of soil, and from that hole the big Lake V�nern was made (V�nern is one of the largest lakes in Europe). He threw the soil as far as he could and the big island Gotland outside Sweden was made. But most giants aren't THAT big!
With a little imagination, a lot of what you see in nature can be seen as memories from the age of giants. Round holes in rocks were thought to be the giants cooking pots. Even today we call these holes "giantpots" in Sweden. When Christianity came to Sweden in the middle of the 12th-century, giants realized that their era was over, so they moved. But it looks like not every giant moved, there have been stories told that people have talked to giants even during this Century.
Giants may be huge, but they aren't very clever. They have a reputation for being very stupid. Besides that, they hate Christianity and throw huge rocks at churches. That is why you often see big rocks close to a church...
A giant can be fooled into helping with the construction of a church. Promise him the sun or the moon in reward for his work. But if the building contractor can guess the giant's name before construction is finished, the giant looses his power and gets nothing!
Giants aren't nice all the time, but they sometimes offer their help. They are good smiths for example. Because they are so big the work is done quickly and besides that, the quality of their forged tools is excellent. As payment you can leave the giant a round loaf and a bottle of vodka.