'High tech' and 'state of the art' are two expressions that describe very modern technology. High tech is just a shorter way of saying high technology. And high technology describes any invention, system of device that uses the newest ideas or discoveries of science and engineering. What is high tech? A computer is high tech. So is a communications satellite. A modern manufacturing(生产) system is surely high tech. High tech became a popular expression in the United States during the early 1980's. Because of improvements in technology, people could buy many new kinds of products in American stores, such as home computers, microwave(微波) ovens, etc. 'State of the art' is something that is as modern as possible. It is a product that is based on the very latest methods and technology. Something that is 'state of the art' is the newest possible design or product of a business or industry. A state of the art television set, for example, uses the most modern electronic design and parts. It is the best that one can buy. 'State of the art' is not a new expression. Engineers have used it for years to describe the best and most modern way of doing something. Millions of Americans began to use the expression in the late 1970's. The reason was the computer revolution. Every computer company claimed that its computers were 'state of the art'. Computer technology changed so fast that a state of the art computer today might be old tomorrow. The expression 'state of the art' became common and popular as computers themselves. Now all kinds of products are said to be 'state of the art'. What is the purpose of the passage?