The science behind the flavor we can detect is usually broken into 4 basic tastes: sweetness, saltiness, sourness, and bitterness. In the last few decades though there has been more evidence of a fifth taste, Umami (savoriness).
Sweetness. Not just a cute pet name for our significant other, this taste can really round out other tastes such as bitterness, saltiness, or sourness. For example, adding even a little bit of sugar to your tomato sauce can really balance out some of the bitter flavor that can come from some tomatoes and tomato pastes.
Allspice, peppercorn, vanilla, star anise, aniseed, mint, cloves, ginger, mace, coriander
Saltiness. Sometimes described as nature's flavor enhancer, it is the most important ingredient in savory dishes, the same way sweetness is to desserts.
Sea salt coarse
Sourness. Sourness can bring a real balance to dishes. Lemon or vinegar can really jazz up fish, lamb, and buttermilk to name a few. A perfect example of this is hollandaise sauce. A heart-stopping good time, this is one sauce every home chef could add to their skillset.
Basil, bay leaf, cardamom, cayenne, chives, cinnamon, garlic, ginger, lemongrass, mint, oregano, parsley, peppercorn, rosemary, sage, sesame, thyme, vanilla
Bitterness. Only needed in small amounts, our taste buds seem readily able to detect even small amounts. Bitterness balances the richness of foods and can clean the palate ready for the next bite. The hotter the food the less we percieve it.
Chicory, fenugreek, basil, thyme, parsley, mint, bay leaves, chives, lemon thyme, turmeric
Umami (Savoriness). Described as the full mouth feeling some foods convey. Tomatoes, mushrooms, cheeses, soy, shellfish, and gravies are great examples of this.
Beef soup base, chicken soup base, onion soup base,