Exterior means the outside or outer surface of something. The exterior of a house includes its walls, roof, and front door: everything you see from the street. The exterior of a car is its painted metal body and windows, while the interior is where you sit.

Architects and designers pay close attention to exteriors because they shape our first impressions. A building's exterior might look welcoming with large windows and a bright entrance, or intimidating with fortress-like walls. When you judge a book by its cover, you're focusing on its exterior rather than what's inside.

In contrast to interior (the inside), exterior describes surfaces and spaces exposed to the open air and weather. That's why houses need exterior paint that can withstand rain and sun, different from the paint used on interior walls.

You might describe someone as having a tough exterior but a kind heart, meaning they seem rough on the outside but are actually caring on the inside. The exterior doesn't always reveal what lies beneath.