Butter is a solid dairy product made of cream by separating the butterfat from the buttermilk.
Butter is water-in-oil emulsion, comprised of >80% milkfat, but also containing water in the form of tiny droplets; texture is a result of working/kneading during processing at appropriate temperatures, to establish fat crystalline network that results in desired smoothness; used as a spread, a cooking fat, or a baking ingredient.