There are two primary reasons to decant a wine.

If the wine is young, exposing it to more oxygen will help it open up. This is true for many whites and every young red wine.

Decant white wines that have the potential to age. Bright, high-acid wines such as Sauvignon Blanc are made to be consumed young, and decanting may actually soften the acidity that gives them their bright, refreshing character. Chardonnay and Viognier often are made in a style that can support aging, and decanting can help.

I’ve done a number of experiments with aerating red wines. At family dinners, we will open a bottle, taste it, give it some air and then taste it again.