The pickled ginger served with sushi is called gari. It is made from thinly sliced ginger marinated in a sweetened vinegar solution and is commonly known in English as sushi ginger.
Young ginger is preferred because it has tender flesh and a naturally mild sweetness. Traditionally prepared gari is pale yellow and may develop a delicate pink tint from very young ginger. Much commercially sold pink gari is colored more strongly with ingredients such as beet juice, red shiso, or permitted food coloring, especially when mature ginger is used.
Gari is usually eaten between pieces or courses of sushi. Its sharp, sweet, acidic flavor refreshes the palate, helping diners notice differences between toppings. It is not the same as beni shoga, another Japanese pickled ginger that is generally julienned and colored red; beni shoga is often served with dishes such as okonomiyaki or ramen. Gari is also not a topping in the same structural sense as fish or nori—it is a side accompaniment.