Salsa may refer to any type of sauce. In American English, it usually refers to the spicy, often tomato based, hot sauces typical of Mexican and Central American cuisine, particularly those used as dips. In British English, the word typically refers to salsa cruda, which is common in Mexican, Spanish and Italian cuisine.
Best known as a chip dip, but also good as a regular old condiment for salads, hot dogs, burgers, and sandwiches. I prefer the hotter salsas because they have more taste and, to me, they represent what I think salsa should be.