Pasta sauce can basically be divided into red sauce and white sauce. Red sauce is based on tomato, and white sauce is based on flour, milk and cream. In addition, there are noodles flavored with olive oil, vanilla sauce, green sauce and squid ink sauce mixed with herbs.
Authentic spaghetti is biting, but it's not undercooked. It feels a little hard. For some people who are used to eating Yangchun noodles in China (mainly in Jiangnan), they may not be used to it. The point is, when cooking spaghetti, you must first add a spoonful of salt, which accounts for about 1% of water. Without this action, noodles will only taste delicious outside, but they will feel tasteless when bitten inside!