"Salsa" is just generic for any sauce that has chile or tomato as a base. most americans equate salsa to the chunky stuff you dip your chips into. Other americans and some northern mexicans call this same thing "pico de gallo" with in a very literal, non-sensical translation means "rooster's beak". Most mexicans just call this "salsa casera", homestyle salsa, or "salsa cruda", raw salsa.
Here is a recipe for this unnameable sauce. This is a raw salsa. No heat touches the veggies, so it's very refreshing.
Start with ripe, but firm tomatoes. romas are best for salsa. Beefsteak and large, round tomatoes are too juicy. cut, not chop. Use a very sharp knife at all times to minimize mushing the tomato. You want cubes about 1cm per side. Do the same with a WHITE onion. never use anything else. Wash the cilatro under lots of cold water. Then let it dry on your dish tray. Wet cilantro will ruin your salsa. dice your onion the same way you did the tomato. Grab one or two serranos. Devein them, cut then to small pieces. Bundle up your cilantro stalks. Cut quickly to small stripts. Don't crosscut. Toss everything together in a dry bowl. throw some salt in there, and VERY few drops of lime juice (never lemon). Stir very little. Taste the simplest, best salsa ever.
The above recipe yields an excellent but very solid salsa. For one that can be poured, blended tomatillos may be added.