Universally why is sugar and salt the key ingredients for making anything taste good?

I believe there's a biological explanation.. something to do with tastebuds being geared up to detect and enjoy those tastes? We need both sugar and salt. so I guess that has something to do with it ... 

I am betting someone else can provide a better and more technically correct answer... lol I am too tired right now to look it up

And fat. Fat is the third item in that triad of things that give palatable taste to our foods.

It is like using stinky whaledrek as the basis for perfumes. Makes the perfume smell travel better.
Or, in this case, make the food taste come through better.

But dont put both salt and sugar in. Then they amplify eachother and the food end up tasting awful.

cause they taste good

I didn't know that to be true...universally.  I don't like mixing the two.....salty ice cream is not for me. 

You forgot about butter.

Of course butter with sugar and butter with salt taste even better.