There are no eggs in butter.
Butter is a dairy product that is made from milk that comes from cows.
Eggs come from chickens and no eggs are added to butter.
Butter contains milkfat which gives the butter a rich flavor and is a dairy product.
Butter contains at least 80% milk fat, around 16% water, 1.5–2.0% salt and 2% other milk solids.
The fat in butter is approximately 67% saturated, 29% monounsaturated and 4% polyunsaturated.
While butter is made from milk and is a dairy product the butter contains little to no lactose (. 003 g lactose per teaspoon) so it can usually be consumed by those who are lactose intolerant.
Grass fed butter that is made from cows milk from grass fed cows is the healthiest butter.
Along with 80% butterfat, the average butter that is sold in the United States contains about 16-18% water and 2-4% additional components, such as milk solids and sometimes salt.