Mexican cuisine is incredibly diverse, and when you start taking a look at authentic Mexican recipes, you can't help but notice the massive role salsas have in shaping the cuisine's flavors. I liked this little article from the Food Network that takes a peek into the major corners of the cuisine and provides a good description of how "salsa" has a much deeper meaning in Mexico than many other countries.
The spicy sauce we buy in jars on supermarket shelves used to taste all the same, but now, at least, there are choices beyond mild, medium and hot. There is green salsa, and salsa punched up with chipotle. You can find habanero-smacked salsa, garlic-heavy salsa and roasted tomatillo salsa. And in Mexico, of course, there are more salsas than could fit in an entire aisle of one of our grocery stores. But then again, in Mexico most of them aren't things you buy in jars; they are things you make.