In Berlin, Germany, currywurst is made using steamed then fried pork sausage. This sausage is then sliced and seasoned with curry, ketchup and other spices. It is a very popular fast food item in Germany.
Each type of sausage has slightly different ingredients, but they are the same in Germany as anywhere else. Usually pork or beef with spices. The primary difference from one type of sausage to another is how the meat is ground up and what spices are used.