A twig is a small terminal branch section that bears leaves, buds and usually the flowers and fruit of plants. Only dicotyledonous flowering woody plants and most gymnosperms have true twigs; monocotyledons and tree ferns do not.

Twigs are critically important in identification of trees, shrubs and vines, especially in wintertime. The buds on the twig are an important diagnostic characteristic, as are the abscission scars where the leaves have fallen away. The color, texture, and patterning of the twig bark is also important, as is the thickness and nature of any pith of the twig.

There are two types of twigs: vegetative twigs and fruiting spurs. Fruiting spurs are specialized twigs that generally branch off the sides of branches and leading twigs, and are stubby and slow-growing, with many annular ring markings from seasons past.