The Silk Road was a group of trade routes that went across Asia to the Mediterranean Sea. This let China trade with the Middle East and the Mediterranean world.

It was called the Silk Road because silk was traded along it. At the time, silk was only made in China, and it was a valuable material. 
The Silk Road not only earned China a lot of money, but all along the route cities prospered and markets flourished. Cities like Samarkand and Bukhara were built largely on the trade from the silk route.

Trade on the Silk Road played a big part in the growth of the ancient cultures of China, Egypt, Mesopotamia, Persia, India, and Rome, and helped to make the beginning of today's world. The term Silk Road is English for the German word "Seidenstraße". The first person who called it that was a German geographer in 1877.

General trading 
Of course, many other things were also traded, even ideas. Because the traders came from many places, different ideas were brought to China, and China's ideas were taken to other places.

Some of the other things traded were porcelain and other types of pottery, food, wine, and spices. Chess pieces from northern India were brought to China and Persia. Paper arrived in the west from China. Metals and jewels were certainly transported, and very likely slaves also. Probably no trader went the whole way along. Goods would be traded on at every stopping-point. Deals might be needed to get past difficult places.

Path 
The Silk Road first traveled west from northern China. Then the part of the Silk Road on land split into two branches. One branch went north of the Tibetan Plateau, and the other branch went south of it.

After the two parts rejoined, it went in an almost straight line west through mountains via Tabriz in north Iran and the north tip of the Syrian Desert to the Levant (Syria, Israel, Palestine). From there Mediterranean trading ships took routes to Italy, and land routes went north through Byzantine Empire or south to North Africa.

The sea route was also called the "Silk Road". It ran from South China, to the Philippines, Brunei, Siam, Malacca, Ceylon, India, Pakistan, and Iran.  In Europe it went between Israel, Lebanon, Egypt, Greece, Balkans, and Italy. Past the Mediterranean Sea, it continued to Portugal and Sweden.

Asian trades 
The Buddhist religion and the Greco-Buddhist culture started to move east on the Silk Road, reaching China from around the second century BC. Trading also helped make many arts and crafts, brought different religions, and food to China. Chinese people helped build the Silk Road. They bought and sold with other people, and built up their culture. 
The Kushan empire, in the northwest part of India, was in the middle of these trades.

The Silk Road brought other cultures into Central Asia and China. It also helped the rise of the Mongol Empire, the largest land empire ever.

The Roman Empire, which bought a lot of Chinese goods, began to fall from power in the West around the 5th century. In Central Asia, Islam expanded starting in the 7th century. This brought a stop to Chinese growth westwards at the Battle of Talas in 751 AD. More growth of the Islamic Turks in Central Asia from the 10th century stopped trade in that part of the world.

Notes

Other websites 

 The history of the Silk Road by Oliver Wild 
 Introduction of the Silk Road from a Turkish tour guide
 Old World Traditional Trade Routes Project 
 Photos of Silk Road China Sights

History of China
Trade routes
History of Asia
History of the Middle East