Brioche Dough is a kind of a sweet bread dough, often used in pastry-making. You can use it simple, or add more ingredients, and create a large variety of products.
Of course, it is a high-calorie dough, as it contains many fats, due to the presence of butter, or lard, or oil. It may also contain milk, eggs, or cream. To make a nicely elastic dough, you need to use flours with a high protein content, that is to say witha high gluten content. For example, all-purpose flour, suitable to make a great Brioche Dough.
In cooking, here in Italy we mainly use Brioche Dough to make breakfast products, like croissant. But, also, to make sweet or savory (if you like the contrast) buns or bundt cakes.
Fun fact: it you want to make Brioche Dough at home, all the ingredients should be at ambient temperature.