Europeans generally have liberal attitudes towards drinking, with the notable exception of Scandinavia (excluding Denmark). The legal drinking age varies between 16-18 in most countries, often with differentiated limits for beer and spirits. In most places drinking in public is both legal, and a common warm weather activity, and police are more likely to give you a warning and send you on your way to bed, than issue fines for drunken or rowdy behaviour. Except on the British Isles, the nightclubs rarely get going until past midnight, head for the bars and restaurants to find people until then.
Europe is by far the biggest wine producing region in the world, France is the biggest and most famous, but 5 of the 10 largest wine exporters are European Nations; France is followed by Italy, Spain, Germany and Portugal, and nearly all European nations have wine production of some scale. Wine production was started 4000 years ago by the Minoan civilization in present day Greece, and was spread across Europe by the Phoenicians and later the Romans. Unlike other regions, European wine producers place much more emphasis on tradition and terroir than on the grape variety, and wines in Europe will typically be labelled by region rather than by its grape, e.g. Chardonnay, unlike the common practice elsewhere. This is because European wine producers claim that their long history have allowed them to adapt production techniques to the unique conditions of their particular region, and things like the soil composition for a region also has much influence on the taste of the wine. Some of the best and most famous wine regions of Europe includes Bordeaux, whose name is as synonymous with its wines as the large city. Another famous French region producing excellent wines is Burgundy (Bourgogne) around the city of Dijon, it produces both red and whites - the most famous ones, often referred to as Burgundies, are red wines made from Pinot Noir or white wines made from Chardonnay grapes. Further north, the Alsace region close to the Germany, and Mosel across the border - grown on some of the continents most dramatic wineyards on very steep hills, are above all known for their excellent white wines. Further to the south, Tuscany in Italy is famous for its Chianti wines made from Sangiovese grapes, while La Rioja is arguably the most popular, and certainly among the best, Spanish wine regions.
In fact, many wine names indicate the place where the wine comes from, with EU laws forbidding use of the name unless it is from a specific place. Examples include Champagne, which has to come from the Champagne region of France, Port which has to come from Porto, Portugal, Sherry which has to come from Jerez de la Frontera, Spain, as well as Tokaji which has to come from Tokaj, Hungary.
While wine is the most popular alcohol in Southern Europe, beer is the national drink for much of Northern Europe. Germany, the Netherlands, Belgium and the Czech Republic make some of the finest brews in Europe and maybe the world. Visitors from many countries, especially those from East Asia or North America will find that European lagers have a richer stronger taste, and often a higher alcohol content than found at home.
Most European nations have a national brand; like Carlsberg, Heineken or Stella, sold most everywhere - but the really good beers are often the smaller brands, which don't try to appeal to everyone. In recent years microbreweries have had a huge revival shooting up everywhere around the continent. If you really want to indulge, try one of the Octoberfests, held in many German cities, the most famously Munich (where they start drinking already in late September!).
Another northern European favourite is cider, most commonly brewed from apples and sold both bottled and on tap in pubs. Taste and alcohol content can vary widely, from dense, cloudy and strong (8% or more) to light, weak (under 4%) and occasionally even artificially flavoured.
As elsewhere vodka, rum and gin are available everywhere. Scandinavia (except Denmark), Eastern Europe and Russia especially have an affection for vodka, and if you've so far only tried the usual suspects like Smirnoff or Absolut; you should try the vodka there; you may just end up surprised at how tasty the stuff can actually be. Elsewhere, most regions have a local speciality that local drinking comrades will happily fill in you, and eagerly wait for your funny faces when your throat and taste-buds screams in agony. Most likely it will be Slivovitz (also called Rakia) in South-eastern Europe and the Balkans (especially in Serbia), a strongly tasting and fruity brandy, usually made from plums. Other forms of brandy, made from grapes instead, such as traditional Brandy, Cognac or Port wine are popular in the UK and South-western Europe. Greece and Italy makes the popular Ouzo/Sambuca which along with the related, resurgent Absinthe, is made from star anise and sugar, giving it a liquorice like taste - watch for the many party fire tricks related to those drinks. In northern Europe you'll likely be served Schnapps (or Aquavit), usually made from fermented hops or potatoes accented by traditional herbs like dill or sloe, be careful, it suddenly kicks in without much warning. Finally, it will hardly come as a surprise to many that Whiskey (or Whisky) is popular with the Scots and Irish. While all these drinks have strong regional roots, you'll generally find one or two types of each, in virtually any bar on the continent.