Stairs are a structure designed to bridge a large vertical distance between lower and higher levels by dividing it into smaller vertical distances. This is achieved as a diagonal series of horizontal platforms called steps which enable passage to the other level by stepping from one to another step in turn. Steps are very typically rectangular. Stairs may be straight, round, or may consist of two or more straight pieces connected at angles.

বিভিন্ন উচ্চতার ভিন্ন ভিন্ন তলকে সংযোগ সাধনের জন্য পরপর কতগুলো ধাপের সুবিধাজনক বিন্যাসই হলো সিঁড়ি ।