Happy Passover!

The most widely celebrated Jewish festival, Passover (which begins at sundown April 19), also known by its Hebrew name Pesach, commemorates the ancient Israelites' liberation from Egyptian slavery.

At a Passover Seder, a celebratory meal, the story of the exodus is retold through readings, rituals and symbolic foods.

While some foods, such as matzo and bitter herbs, are required eating, others (including bread) are forbidden. Traditional Jews can't even store the taboo items in their homes or eat from dishes or cutlery that have touched them.

The Seder consists of 15 rituals, most of which occur before the meal is served. They include lighting candles, blessing wine, washing hands, breaking the matzo, dipping vegetables and telling the story of the exodus from Egypt.

Passover lasts eight days and begins with two nights of Seders. Traditions vary greatly depending on a family's background. While many Ashkenazi Jews won't eat legumes, corn, rice, most other grains or products made from them, Sephardic Jews are more lenient.

Most Jews eschew the "the five species of grains" — wheat, rye, oats, barley and spelt, all of which contain gluten.

The exception is matzo, which is made from wheat, but has not been allowed to ferment. Matzo must be baked within 18 minutes of the flour being combined with water.