Barong is actually short for Barong Tagalog, which describes the formal men's wear of the Philippines. It is properly referred to as the 'Baro ng Tagalog' (dress of the Tagalog). Contracting the first two words produces 'Barong,' which literally means 'dress of.' So, if we want to be correct, we wouldn't say just 'Barong.' But, the slang way of referring to one of the beautiful formal shirts is simply Barong. Yes, the Barong Tagalog is a dress, a garment, a coat in itself. It is not merely a 'shirt'. If it were, then it would need a coat or a jacket over it to qualify as formal wear and would have to be worn tucked inside the trousers.
In Batangas, Taal town is known for producing this product. But unlike other barong products, theirs are made from jusi or pinya(pineapple fibers) which includes intricate cutwork and crochet insertions. That is why Barong Tagalog from Taal is popular worldwide.