V-8 is both a brand trademarked by Campbell's and a generic term for tomato-based vegetable juice.
V-8 ® Vegetable Juice is a trademark name for a beverage made from the juices from either eight vegetables or a mixture of both fruit and vegetables. The brand is owned by the Campbell Soup Company and is seen as a more healthy alternative to juice drinks such as Five Alive.
Several variants on the basic V-8 platform are available, such as Low Sodium and High Calcium.
Campbell's also produces sweet fruit juice cocktails under the V-8 brand, adding fruit juices with carrot juice.
The name derives from the "eight vegetables" it is produced from: beet, celery, carrot, lettuce, parsley, watercress, spinach and tomato (though tomato is actually a fruit) and was intended to evoke the power of the V-8 gasoline engines of the era (around 1948).
Multiple variants have been produced over the years, with varying degrees of flavour differentiation between them, including Lemon, Organic, Spicy Hot, Picante and Low Sodium, among others. Campbell's also markets a line of "V-8 Fusion" drinks that are essentially carrot/fruit juice combinations that should NEVER be confused for "real" V-8 tomato-base products in mixing applications.
V-8 can be enjoyed chilled "neat" or with some lemon and/or a dash of salt and/or pepper (alternatively with a dash of Tabasco sauce or Worcestershire sauce) or on the rocks. Some prefer it hot, as a soup.