Vines like Clematis are plants whose stems require support external to their inherent structure. They are either woody or herbaceous and climb up trees, trellis, fences, or even walls.
Without a structure to grow on, they would sprawl over the ground. Vines climb with tendrils that naturally wrap around a support structure as they grow.
A woody vine has a stem that persists year-round, adding new growth onto older wood each year. Woody vines have a hardened, lignified stem that lasts for multiple seasons. They are typically considered shrubs or perennials, meaning they live for multiple years and can grow quite large. Examples include wisteria, grapevines, honeysuckle, and clematis to name a few.
In contrast, herbaceous vine dies back to the ground each winter and regrow from the roots in the spring, meaning its stems are not woody and are considered soft and flexible. They can be an annual (completing their life cycle in one year) or a perennial (returning year after year).