The sunflower seed is the fruit of the sunflower (Helianthus annuus). There are three types of commonly used sunflower seeds: linoleic (most common), high oleic, and NuSun developed for sunflower oil. Each variety has its own unique levels of monounsaturated, saturated, and polyunsaturated fats. The information in this article refers mainly to the linoleic variety.

For commercial purposes, sunflower seeds are usually classified by the pattern on their husks. If the husk is solid black, the seeds are called black oil sunflower seeds. The crops may be referred to as oilseed sunflower crops. These seeds are usually pressed to extract their oil. Striped sunflower seeds are primarily used for food; as a result, they may be called confectionery sunflower seeds.