If you touch your tongue, you'll notice that it's covered with bumps and mini-ridges. Each of these bumps is made up of taste buds, which in turn are made up of taste receptors. Our mouthshave between 2,000 and 4,000 taste buds in total, and each taste bud has between 10 and 50 receptors. In other words, humans are well-equipped to savor different foods.
All of our taste buds help us to perceive five types of flavors: sweet, salty, sour, bitter and umami. (That last term describes savory foods, like cured meats, mushrooms and fermented cheeses.)
The act of tasting is a bit like a chemical puzzle. When we chomp into something, that food releases molecules that have certain shapes, and these shapes float around in our mouths. Each flavor of food has a unique shape, which matches up to a type of taste receptor with a corresponding shape. For instance, when the bitter molecules from our lunch time arugula salad bind to a bitter receptor, that sends a series of neural signals to our brain announcing that we've tasted something bitter.