Emmental looks more like the popular image of cheese than any other type; watch any cartoon or animated film, and if there's cheese in it, it's almost certainly a wedge riddled with Emmental's characteristic holes.
Emmental is sometimes referred to as 'Swiss cheese' but that is a broad classification because many varieties are produced in Switzerland. Swiss cheese made outside Switzerland resembles Emmental because it has large holes but it is mass produced and usually has less flavour.
Real Emmental has PDO (protected designation of origin) status, so any cheese labelled with the name should have been made in the Emmental region. The best Emmental has the AOC (appellation d'origine controlee) label, meaning it's made under strict guidelines from raw cow's milk then aged for at least four months. The longer the cheese ages, the larger the holes, which come from the gases released during fermentation. Even the holes are subject to inspection - there must be a certain number and they have to be a certain size.
When young, Emmental has a subtle, mildly sweet flavour; it gets sharper, nuttier and more complex as it ages. It's sold at the cheese counters in Great, Citysuper and Oliver's.