A perfumer is a term used for an expert on creating perfume compositions, sometimes referred to affectionately as a Nose (French: le nez) due to their fine sense of smell and skill in producing olfactory compositions. The perfumer is effectively an artist who is trained in depth on the concepts of fragrance aesthetics and who is capable of conveying abstract concepts and moods with fragrance compositions. At the most rudimentary level, a perfumer must have a keen knowledge of a large variety of fragrance ingredients and their smells, and be able to distinguish each of the fragrance ingredients whether alone or in combination with other fragrances. As well, they must know how each ingredient reveals itself through time with other ingredients. The job of the perfumer is very similar to that of flavourists, who compose smells and flavourants for many commercial food products.