Today's lecture is about the history of the bicycle. The first bicycle, invented in the early 19th century, had no pedals; riders pushed their feet along the ground. Later, the penny-farthing, with its large front wheel, became popular in the 1870s. However, it was dangerous because riders sat high above the ground. The modern safety bicycle, introduced in the 1880s, featured two equal-sized wheels and a chain drive, making it much safer and more practical. This design quickly replaced the penny-farthing and became the basis for today's bicycles.