Nectar is a viscous, sugar -rich liquid produced by plants in glands called nectaries or nectarines, either within the flowers with which it attracts pollinating animals, or by extrafloral nectaries, which provide a nutrient source to animal mutualists, which in turn provide herbivore protection.

Nectar in flowers serves chiefly to attract pollinators, such as fruit-eating bats, hummingbirds, sunbirds, and insects. Nectaries are usually located at the base of the flower stamens, which draw animal visitors into contact with the pollen to be transferred.

Plants have evolved to produce nectar to attract pollinators that feed upon the nectar and assist in pollination by brushing against the reproductive parts of a flower and picking up or depositing pollen to complete the fertilization process. In return, the pollinators receive a source of energy from the sugar-rich nectar they consume.