In Italy, various consortiums regulate the appellations, but not stringently. For example, although there are many Chiantis from Tuscany, the Chianti consortium generally let the wineries sell these wines, even if they don't meet the standard definition of what makes a "Chianti". However, they do designate what makes a Chianti Classico. So if you want to drink an 'authentic' chianti while you are playing online casino, look for the 'classico' designation. This applies to a handful of exported , well known Italian wines.
The last question "How" actually ends up being two questions
How were the grapes picked? and/or How was the wine defined?
How were the grapes picked? This is a broad category, to be sure, but I felt it needed to be covered. German wines have terms for when the grapes were picked and how ripe they were. Since this is a taste issue, I'll refrain from telling you which is the better designation but I will say that these four definitions are part of a larger definition of German wine which I'll touch upon further below:
You'll also see "Eiswein", which literally means 'ice-wine' indicating that the grapes were picked when frozen.
How was the wine defined? The Wine can be defined in many ways...below are several terms that should help out. Some are regulated by their specific authorities, others are traditional terms that have no standards to be based upon.
German wines Germany loves labeling their wines. You find more information on German Labels than you find on other countries labels. The Germans even tell you how dry the wine may or may not be:
Trocken - A dry wine without perceptible residual sweetness.
Halbtrocken - A semi-dry wine with a barely perceptible sweetness.
German wines also can have determinations for quality (much like the French):
Deutscher Tafelwein - German Table Wine. Lower in quality. Made from normally ripe and slightly under ripe grapes.
Landwein - Country wine....consider this a superior table wine.
Qualittswein bestimmter Anbaugebiete (QbA) - Quality Wine of a Specified Appellation, these wines have to follow appellation laws in order to be designated as an appellation.
Qualittswein mit Pradikat (QmP) - Quality Wine with Attributes , only these wines can be given the "Kabinett, Spatlese, Auslese, BA, and TBA". If you see these designations on your German wines, you are getting a perceived higher quality wine.
French Wines The French like to list the quality of the wines on their bottles as well. Sometime you will also see these terms on non-French bottles.