The Stone Age is a time when people mainly relied on tools made of stone. The Stone Age is of different lengths in different parts of the world, depending on when people first started to make use of metals. Metals were first used in the Middle East, and so the Stone Age ended here while in other places such as Britain, it continued for thousands of years more. In the Americas it lasted more or less until the time of the arrival of European explorers. Notice that the Stone Age says nothing about how civilised people were. When the Spanish arrived on the shores of the Aztec Empire of South America, for example, the Aztec had writing and a very complicated society, so although they did not use metals, they were civilised.
The Stone Age in Europe and the Middle East is divided into three ages. These are the Old Stone Age (also known as Neolithic), the short Middle Stone Age (also known as Mesolithic) and the last part of the Stone Age called the New Stone Age (and known as the Neolithic). Lithic is Latin for Stone.
The Old Stone Age is the longest period of time. It began about two million years ago when humans first used stone tools. At this time humans lived in small family groups and wandered through the countryside searching for animals to hunt, and collecting fruits and roots to eat. These people were called hunter-gatherers because they hunted animals and gathered food from plants. They used stone to make axes, to chop down trees and to break up bones. They made bone scrapers to clean the flesh of animal skins, so the skins could be worn as clothes.
The Middle Stone Age (12,000 - 6000 years ago) was quite short. It was the time when the last part of the Ice Age ended and ice sheets melted. As a result, sea levels rose and Britain, for example became a group of islands. This was also the time when farming began, although that mostly happened in the Neolithic.
The New Stone Age (in the Middle East, South and East Asia) began about twelve thousand years ago when people began to settle down and farm the land for food instead of wandering. Stone was used to make the blade of a hoe. This is a tool for breaking up the ground before crops are planted. Stone was also used to make the blades for sickles. These tools were used to cut down the crops that people grew on their farms. In the New Stone Age people also learnt how to make pottery and to weave cloth. The Stone Age ended about six thousand years ago when people began to use Bronze instead of stone to make tools. The Neolithic started and ended later in Britain than in the Middle East because it took time for ideas of using metal to spread.
Remember, the Stone Age does not mean people were primitive. The Sumerians, the Egyptians, the Aztec and Maya all belonged to the Stone Age, at least for part of their existence, but still built amazing cities and could write. But they had not learned to make use of metals. The word Stone Age was also meant to describe events in Europe and parts of Asia. It was not meant to refer to places in the Americas, where different time lines apply.