Generally it is made with either cabbage or sauerkraut and other winter vegetables, although meat can be added. Shchi made of sauerkraut have a sour taste and are called sour shchi. A summer sorrel soup, popular in pre-Revolutionary Russia, was known as green shchi (Russian: Зелёные щи, zelyonye shchi). Usually smetana is added into shchi before serving.
Trivia
The two-letter word щи is transliterated into 5 letters in English. The German word for it is Schtschi, (8 letters, i.e., the word becomes 4 times longer, a feat hardly surpassable for any pair of languages). This was the gist of a joke about Catherine the Great, a tsarina of German descent: it was said that her Russian spelling was so bad that she made up to 8 errors in a 2-letter word.
There is a Russian saying: Щи да каша - пища наша (shchi da kasha - pishcha nasha): "Shchi and kasha are our staples."
