There can be savory or sweet raita. Based on your region in India, some may contain tomatoes and onions while others may not, sometimes seasonal fruits or beets or mint is add, it can be done in many ways...the recipe here is for the most famous raita which is popular all over the country. This is also called Boondi Raita, for which you will need to buy Boondi from the store. Boondis are deep fried chickpea flour balls which are very small and are sometimes spiced.
2 cups low-fat plain yogurt, whisked
1/2 cup cilantro, finely chopped
1/2 teaspoon cayenne OR LESS
1 teaspoon fresh grated ginger
1 teaspoon cumin seeds
1 teaspoon sugar
1/2 teaspoon salt
1/2 cup Boondi (spiced fried chickpea balls) OPTIONAL
In a mixing bowl, mix all the ingredients and chill. Serve cold with main meal.