Italian sausage is a type of pork sausage that is seasoned with a variety of spices, including fennel, garlic, and red pepper flakes. It is commonly used in Italian cuisine, adding flavor to dishes like pasta, pizza, and sandwiches. There are two main varieties of Italian sausage: sweet and hot. Sweet Italian sausage is flavored with sweet basil and has a milder taste, while hot Italian sausage contains red pepper flakes for a spicier kick. Both types can be found in links or bulk form, making them versatile for cooking.