Oak is a common flavoring element that typically contributes flavors and aromas of vanilla, smoke, toast, cedar and spices like nutmeg, cinnamon and dried ginger. Other, more subtle oak influence often comes across as coconut, dill, coffee and milk chocolate.
There are two main categories of oak, referred to as American oak and French oak. The American oak adds more sweetness and vanilla flavors to the finished wine, with coconut and dill being very typical indications of its use. French oak is generally more subtle in its effects, adding cedary elements, spices and cigar box aromas.