Plants annual or perennial herbs (shrubs, small trees, or rarely lianas elsewhere), sometimes with rhizomes or stolons. Aerial stems absent or, if present, then erect or ascending (sometimes becoming lax with age), unbranched or few-branched. Leaves all basal or (in taxa with aerial stems) also alternate (the lowermost leaves sometimes opposite or subopposite), short- to long-petiolate, the blades simple, but sometimes deeply lobed, the margins otherwise entire to more commonly toothed or scalloped. Stipules often conspicuous, usually herbaceous, entire or more commonly toothed or lobed, sometimes irregularly so. Inflorescences of solitary or rarely clusters of 2 or 3 axillary flowers (these appearing basal in taxa not producing aerial stems; elsewhere grouped into heads, racemes, or panicles), the flowers short- to long-stalked, bractless or (in Viola) with a pair of small, herbaceous bracts positioned variously on the stalk, in some species the late-season flowers usually cleistogamous. Flowers mostly strongly zygomorphic (less so in Cubelium), perfect, hypogynous. Calyces of 5 free sepals, these somewhat overlapping, some or all of these sometimes with a small pouchlike auricle at the base, usually persistent at fruiting. Corollas of 5 free petals (these undeveloped in cleistogamous flowers), the lowermost petal slightly longer than (in Cubelium) to somewhat shorter than (in Viola) the upper pair, often (in Viola) with a basal spur. Stamens 5 (reduced to 1 or 2 in cleistogamous flowers), the filaments sometimes somewhat fused, appearing very short but sometimes extending beyond the anthers into tapered, terminal appendages (in Viola), the relatively stout anthers appressed to and usually fused into a tube around the pistil, the lowermost pair (or sometimes all of the anthers elsewhere) often with a basal spur. Pistil 1 per flower, of 3 fused carpels, the ovary superior, 1-locular, the placentation parietal. Ovules 3 to many Style 1, often asymmetrically expanded toward the tip, the stigma often positioned obliquely or appearing obliquely lobed. Fruits capsules, with 3 relatively thick valves, dehiscing longitudinally between the placentae (sometimes explosively), the edges of the valves usually curling inward along the sides as they dry. Seeds sometimes with arils. Twenty-three genera, about 830 species, nearly worldwide.

The family’s main economic importance is in horticulture. A number of species of Viola are cultivated as ornamentals in gardens as are a few species in other genera. However, African violets belong to the genus Saintpaulia H. Wendl., which is in the tropical family Gesneriaceae. The flowers of some Viola species are occasionally used fresh as garnishes in salads, cooked as potherbs, or candied as decorations for other foods. Members of the Midwestern genera have a limited use in folk medicine, mainly as an infusion or syrup for respiratory ailments or digestive troubles. In folklore, violets are a symbol of fertility and have thus been used in love potions.

Although Midwestern botanists are familiar with members of the Violaceae as relatively small herbs, most of the family’s taxonomic diversity in tropical regions is in the form of shrubs and small trees (the largest tropical genus, Rinorea Aubl., contains about 300 species).