Chard (/tʃɑːrd/ ^ⓘ; Beta vulgaris subsp. vulgaris, Cicla Group and Flavescens Group) is a green leafy vegetable. In the cultivars of the Flavescens Group, or Swiss chard, the leaf stalks are large and often prepared separately from the leaf blade; the Cicla Group is the leafier spinach beet. The leaf blade can be green or reddish; the leaf stalks are usually white, yellow or red.

Chard, like other green leafy vegetables, has highly nutritious leaves. Chard has been used in cooking for centuries, but because it is the same species as beetroot, the common names that cooks and cultures have used for chard may be confusing; it has many other common names such as silver beet, perpetual spinach, beet spinach, seakale beet, or leaf beet.

Chard was first described in 1753 by Carl Linnaeus as Beta vulgaris var. cicla. Its taxonomic rank has changed many times: it has been treated as a subspecies, a convariety, and a variety of Beta vulgaris. (Among the numerous synonyms for it are Beta vulgaris subsp. cicla (L.) W.D.J. Koch (Cicla Group), B. vulgaris subsp. cicla (L.) W.D.J. Koch var. cicla L., B. vulgaris var. cycla (L.) Ulrich, B. vulgaris subsp. vulgaris (Leaf Beet Group), B. vulgaris subsp. vulgaris (Spinach Beet Group), B. vulgaris subsp. cicla (L.) W.D.J. Koch (Flavescens Group), B. vulgaris subsp. cicla (L.) W.D.J. Koch var. flavescens (Lam.) DC., B. vulgaris L. subsp. vulgaris (Leaf Beet Group), B. vulgaris subsp. vulgaris (Swiss Chard Group)). The accepted name for all beet cultivars, like chard, sugar beet and beetroot, is Beta vulgaris subsp. vulgaris. They are cultivated descendants of the sea beet, Beta vulgaris subsp. maritima. Chard belongs to the chenopods, which are now mostly included in the family Amaranthaceae (sensu lato).

The two rankless cultivar groups for chard are the Cicla Group for the leafy spinach beet and the Flavescens Group for the stalky Swiss chard.

The word "chard" descends from the 14th-century French carde, from Latin carduus meaning artichoke thistle (or cardoon which also includes the artichoke) itself.

The origin of the adjective "Swiss" is unclear. Some attribute the name to it having been first described by a Swiss botanist, either Gaspard Bauhin or Karl Koch (although the latter was German, not Swiss). Be it as it may chard is used in Swiss cuisine, e.g. in the traditional dish capuns from the canton of Grisons.

Chard is a biennial. Clusters of chard seeds are usually sown, in the Northern Hemisphere, between June and October, the exact time depending on the desired harvesting period. Chard can be harvested while the leaves are young and tender, or after maturity when they are larger and have slightly tougher stems. Harvesting is a continual process, as most species of chard produce three or more crops.

Cultivars of chard include green forms, such as 'Lucullus' and 'Fordhook Giant,' as well as red-ribbed forms, such as 'Ruby Chard' and 'Rhubarb Chard.' The red-ribbed forms are attractive in the garden, but as a general rule, the older green forms tend to outproduce the colorful hybrids.^{[citation needed]} 'Rainbow Chard' is a mix of colored varieties often mistaken for a single variety.