A fair is often a temporary amusement event. This is a travelling funfair (also sometimes known as a carnival in North America). Most people simply call them 'fairs'. A fixed fair is called an amusement park.
The word fair comes from the Latin word feria, meaning a holiday.
Typically, the travelling funfair is advertised under the name of the fair owner, but the individual rides and stalls are run by different, independent showmen.
Fairs began in medieval times as simply a collection of market stalls, but people going to fairs on foot wanted to make their journey into something of a holiday and so showmen began to attend fairs.
Fairground rides were invented much later on. The first fairground rides date from the eighteenth century. The 'engines' to make them work were gangs of boys pulling on ropes. By the middle oft eh 19th century steam power began to be used with a steam engine inside each ride. The rides were then moved by long belts attached to the engine. The extra power meant that the rides could be faster and more exciting. This is when the funfair became mainly a place of entertainment, and less of a place to buy and sell goods.