Most white wine is produced from white grapes. I say most, because there are a few exceptions. Wine gets its colour from letting the skins soak in the juice.
Since this is the case, it is possible to make white wine out of black grapes by carefully extracting the juice and keeping the skins separated. Champagnes such as G.H.Mumm or Perrier Jouet, is the most famous example. It is made from a blend of grapes which include Pinot Noir and Pinot Meunier (black grapes).
Besides colour, not allowing the skins and stems to soak in the juice also reduces the amount of tannin in the wine. Tannin has a mouth drying quality that causes the wine to feel firm in your mouth. This is the same effect in Chinese tea. Sometimes though, a white wine will be allowed to ferment or age in oak barrels. The oak barrels will impart some tannin to the wine, but not as much as in a typical red wine.

Rosés are White?

Believe it or not, a rosé, is considered a white wine. They are made by allowing the skins to soak for only a short period of time before extracting. A good rosé such as Jacob’s Creek Shiraz rosé should be delicate and refreshing, not syrupy sweet.
Rosés have been given a bad reputation from some of the extremely sweet and cheap varieties on the market. Don't let that stop you from finding some that are truly delicious and worth enjoying.

Major White Wine (Grape) Varieties

Chardonnay - The world's most popular white variety. It is usually oak aged and has a buttery flavor.
Chenin Blanc - Common in the Loire Valley of France and South Africa. It is a highly acidic wine that can range from very dry to very sweet.
Gewürztraminer - The most intensely aromatic of all wines. The aromas are of lychees, floral and spice.
Riesling - A very wide variety of styles from bone dry to sweet to spicy. Often they will have hints of lemon, lime and minerals, such as Jacob’s Creek reserve Riesling.
Sauvignon Blanc - Meant to drink young, these are the most tangy and pungent of the wine varieties, especially the ones from New Zealand’s largest producer Montana.
 

Other White Wine (Grape) Varieties

Pinot Blanc - Highly acidic and low sugar levels resulting in a dry, crisp wine.
Torrontés - The popular white grape from Argentina. It produces a highly aromatic and seemingly sweet wine, even though dry. Good examples include Bodega Etchart’s Privado Torrontés.
Verdelho - A rich, white wine with the taste of limes.
Viognier - A low acid wine with floral aromas and an apricot quality. It is so richly aromatic that even though it is dry, it seems sweet.

European White Wines

The Europeans label their wines by the region in which the grapes are grown, not the grape variety like in the Australia. Many times they are blends of multiple grape varieties. Here is a chart of some of Europe's white wines.

Region	Country	Grape Varieties
Bordeaux	France	Sauvignon Blanc, Sémillon, Muscadelle
Burgundy	France	Chardonnay
Chablis	France	Chardonnay
Champagne	France	Chardonnay, Pinot Noir, Pinot Meunier
Mosel	Germany	Riesling or others
Pouilly-Fuissé	France	Chardonnay
Rhine/Rheingau	Germany	Riesling or others
Sancerre	France	Sauvignon Blanc
Sauternes	France	Sémillon, Sauvignon Blanc
Soave	Italy	Garganega and others

Enjoying White Wine

White wines are typically less complicated than reds because of the effect tannin has on red wines. Therefore, white wine can be enjoyed whenever and where ever the mood strikes you. White wines can make an excellent apéritif or before dinner drink instead of a cocktail. They are also the least likely to offend the palate of a novice wine drinker.
Most people know to drink white wine chilled, but it can be too cold. Yes, I know, you're not going to get a thermometer and take the temperature of the wine every time you are going to drink it. What I would recommend is to actually drink wines at slightly different temperatures until you get a feel for them.
With practice, you will have a good idea of the approximate temperature.

General Temperature Guidelines

• Simple and dry white wines should be consumed at the coolest temperature.
• Complex, heavier wines should be consumed at the warmest temperature (but still cool) of the other whites.
• More expensive, higher quality wines should generally be served at the warmer temperatures.
• Less expensive wines generally need to be served at lower temperatures.

The important thing to know is that a white wine needs to be refreshingly cool, but if its too cold, you will lose the subtle nuances of that expensive chardonnay.

Tip - It takes about 3 hours to chill a bottle of wine down to the temperature of the refrigerator. To quickly chill a bottle of white wine, fill a bucket full of ice water. Add some salt and then put the bottle in and twist several times. This causes more of the wine inside the bottle to come into contact with the cold glass. Let sit and occasionally repeat twisting for a few minutes. I wouldn't recommend this with sparkling wines as it might cause the cork to explode out of the bottle!