One of the first things to know about them is that daytime for humans, is nighttime for trolls. Also, Danish trolls aren’t as big as other Nordic trolls. Swedish trolls are similar in size although a bit larger but Icelandic and Norwegian trolls are much bigger by comparison.
In Denmark, trolls are around the size of a ten year old child but with a heavier build. They have big ears and noses as well as a tail. They have rough, ugly features. For trolls, tails are said to be the source of their power, common sense and feelings. Because of these reasons, trolls often hide their tails which has led to inaccurate conflicting reports that suggest that some trolls don’t have tails.
Trolls are characterized as being strong, naïve and primitive. They are in possession of magical powers and can live to be hundreds of years old without appearing to be old. They live in hills, caves, forests, and fields. They are known for reciprocating whatever way you treat them - so they can reward you handsomely for being kind to them, and keep you captive in their caves if you wrong them. Trolls have been inaccurately described by some as eating small children. They eat nuts, berries, mushrooms, as well as frogs, mice, and potatoes.
Lastly, they can use magic to make themselves invisible, or make themselves look like humans. Their only distinguishing feature in some cases is their tail which they try to keep hidden.
Troll facts from: Troldhuset