A wine score is the quickest, simplest way for a wine critic to communicate their opinion about the quality of a wine. Often found alongside tasting notes, wine scores help consumers and collectors decide which wines to buy, and can be a powerful marketing tool.

The 100-point scale is the most common method for scoring wines. However, several key critics use a 20-point scale, and a some even use a 5-point scale.

100-Point Scale
The 100-point wine-scoring scale was popularized by Wine Spectator magazine and by Robert Parker in his Wine Advocate newsletter. The effect of a high score from either publication is hard to understate, and can make or break a wine brand (see these lists of Wine Spectator Top 100 Wines and Robert Parker 100-Point Wines).

There are many who question the value of the 100-point scale, typically because almost all wines evaluated fall within a narrow band between 85 and 100 points. The system is based on the American high-school marking system, so the scale starts at 50 (rather than 0), which has led to further criticism. Despite this the 100-point scale is used by more and more critics – amateur and professional – with each year that passes.

Score Explanation
95–100 Classic: a great wine
90–94 Outstanding: a wine of superior character and style
85–89 Very good: a wine with special qualities
80–84 Good: a solid, well-made wine
75–79 Mediocre: a drinkable wine that may have minor flaws
50–74 Not recommended

20-Point Scale
The 20-point scale for wine scoring first emerged in 1959. It was developed purely for academic wine evaluation, by Dr Maynard Amerine of UC Davis’ much-respected Viticulture & Enology department. On this original scale, points were attributed for color, aroma and flavor, as well as more technical qualities including the balance of sugars, acids, tannins and volatile acidity. Even today the 20-point scale retains a slightly technical, traditional feel.

Score Explanation
20 Truly exceptional
19 A humdinger
18 A cut above superior
17 Superior
16 Distinguished
15 Average
14 Deadly dull
13 Borderline faulty or unbalanced
12 Faulty or unbalanced

5-Point Scale and other systems
5-point scales most often use stars (or other symbols) rather than points per se.Other guides highlight top-quality wines with an asterisk (two for truly exceptional wines).

Score Explanation
5 Stars Superlative. A Cape Classic
4 Stars Excellent
3 Stars Good Everyday Drinking
2 Stars Casual Quaffing
1 Star Very Ordinary

Source: wine-searcher.com