One of the greatest inventions of man was the invention of wheels. Imagine the world without wheels! There would be no cars, buses, motorcycles, and trucks, literally no means of transport other than by foot or horseback. Today we have different kinds of wheels made from different material. Wheels are used in almost all modes of transportation — trains, buses, trucks, cars, aeroplanes, scooters, cycles, rickshaws, bullock carts, etc. The invention of wheel has enabled us to cover long distances in a short time. How was this wonder invention made? During the stone ages before the invention of wheel, man carried all loads himself. Later, animals like oxen, donkeys, horses and camels were tamed and used for carrying load. This was done by dragging loaded wooden planks with the help of animals. Later Stone Age man learnt to roll the loads on logs, usually downhill. The oldest known wheels were nothing but rounded slices of wood cut across a log with a hole in the centre. Soon after the primitive wheel was made, two wheels were joined by an axle and fastened to a platform of wood. This could be considered as the first crude cart made in the world. In this cart, both the wheel and the axle moved. Later, with passage of time, more advanced versions of the wheel were developed. Recorded history says that wheels were very much used in ancient Mesopotamia (Modern Iraq) between 3500–3000 B.C. The picture of a cartwheel appears on some clay tablets from Mesopotamia dating to this era. Studies reveal that wheels were in use in Indus valley during 2500 B.C. The next innovation in the use of wheel was the fixed axle. The axle was fastened to the vehicle and the wheels were allowed to spin freely which enabled faster movement. The first wheeled vehicles were bullock, horse and camel carts, chariots, two and four-wheeled carts for goods and other similar vehicles. Later around 2000 B.C., Asians invented the spoke wheel that reduced the weight of the wheel to a great extent. With the passage of time, numerous improvements have been made in the design of wheels. Today, we have the rims and spokes of wheels made of metals such as iron, steel, aluminium alloy etc. Rubber tyres and tubes are put around them to facilitate smoother movement. Different types of tyres have also been designed for comfort and stable driving. Now the wheel has become lighter, more efficient and long-lasting, and almost one of the essentials of life.