Not all of them. A convection oven is one with a fan that circulates hot air around the food for even heating. Many home ranges and wall ovens include a fan or convection setting, but a basic conventional oven has no fan and relies on natural convection, so it runs cooler at the bottom and hotter at the top.
Fan-assisted convection cooks food faster, which is why recipes often suggest lowering the temperature or shortening the time when using it. Small countertop convection ovens for home use are commonly sold as air fryers.
Source: Convection oven, Wikipedia
Image: Tabletop convection oven by Bagoto, CC BY-SA 4.0, via Wikimedia Commons.