A Brioche is a French viennoiserie, which is a baked dough good similar to bread, but has many elements in common with a pastry: it contains eggs, butter, milk and cream. A brioche bun usually has a quite puffy, light and soft texture.
Brioche have many uses in French cuisine, and can be eaten plain for breakfast, dessert or as a snack, with various different fillings and ingredients.
The origins of the word brioche are debated, but there is now a general consensus that brioche derives from the Old French verb "brier", which means to work the dough with a "brie", a wooden roller.
The correct pronunciation of the word brioche in French can be phonetically written as bree-osh. The "r" at the beginning is pronounced with a slightly rolling French "R", which may be hard to pronounce for English speakers. However, even without that "R" it is possible to have a good enough pronunciation of brioche. Successively, the "o" in -osh must be pronounced in a slightly closed manner, similar to the "o" in the word "off".