Bars
The Netherlands has two drinking ages: 16 years for alcohol under 15% (beer, wine, etc), and 18 for all other drinks.
Beer
Although the Dutch beer "Heineken" is one of the world's most famous beers, it is just one of the many beer brands in the Netherlands. You can get all kinds of beers from white beer to dark beer. Popular brands are Heineken, Grolsch, Brand, Bavaria, Amstel etc.
In addition to the usual lagers, try Dutch wheat beers (witbier), which are flavored with a spice mix called gruit and thus taste different from the better-known German varieties. Fruit-flavored varieties are also available.
Traditional beers come from monasteries in the South of the Netherlands (Brabant and Limburg) or Belgium. You can visit a traditional beer brewer in for instance Berkel-Enschot (just east of Tilburg) at the 'Trappistenklooster'. It needs to be said that the brewery is now owned by the big brewer Bavaria, so it's not so traditional any more.
Most breweries have nowadays also produce a non-alcoholic variant of their beers, like Bavaria Malt or Amstel Malt. Which consist sometimes 0% or less than 0,5 alcohol and is very suitable for people who would like to drive and don't drink (or sometimes called "de Bob" as promoted in its campaign).
Bitters and gin
Also popular in winter are alcoholic bitters. Originally from the province of Friesland the bitter called Beerenburg is served in the entire country. Most other regions also produce their local, less famous variants of a bitter.
- Orange bitter (Oranjebitter), this bitter liquor is drunk only on Queen's Day (Koninginnedag)
- Dutch gin (jenever or genever), the predecessor of English gin. It's available in two types, called oude (old) and jonge (young), which have nothing to do with aging, just the distillation style. The more traditional "old-fashioned" oude is sweeter and yellowish in color, while jonge is clearer, drier and more akin to English gin.
Tea and coffee
Dutch drink black tea, and it comes in many different tastes, from traditional to fruit infusions etc. Luckily, if you're English, you get the teabag served with a cup of hot (but never boiling!) water, so you can make your own version. Milk in your tea is almost unheard of and only given to children.
Coffee is almost compulsory when you are going to visit people. One of the first questions when coming through the door is often "Koffie?" and it is served in small cups (a half mug) with cookies.
If you're from the States or Canada, you can drink one cup of Dutch coffee in the morning and add water the rest of the day! If you order 'koffie verkeerd' (which means "coffee the wrong way 'round") you get a cup of mostly hot milk with a small splash of coffee -- more like the French 'café au lait' or the Italian 'latte'.
Hot chocolate
Hot chocolate with whipped cream is a winter tradition in the Netherlands. It really fills you after a cold walk. In the summer you can also get it in every decent bar, however sometimes it's made from powder as opposed to the traditional kind, and doesn't taste that good.