1, Princeton University: world ranking 1, Massachusetts Institute of Technology: world ranking second, Harvard University: world ranking third, Stanford University: world ranking third, Yale University: world ranking third, Chicago University: world ranking sixth, Johns Hopkins University: world ranking seventh.

2. The University of Pennsylvania ranks seventh in the world, the California Institute of Technology ranks ninth in the world, and Duke University ranks 10 in the world.

The significance of ranking is as follows:

1. evaluation and comparison: ranking can provide an opportunity to compare and evaluate different individuals or things. For example, in the field of education, students can evaluate their performance in a certain course according to their grades. Similarly, when recruiting employees, the company may rank job seekers according to their skills and experience to determine whether they meet the requirements of the position.

2. Reference: Ranking can provide useful reference information for decision makers, investors and consumers. For example, investors can evaluate the investment potential according to the company's financial data and performance ranking. Consumers can choose the most suitable goods or services according to the price, quality and satisfaction ranking of products.

3. Discover strengths and weaknesses: Through ranking, individuals or organizations can discover their strengths and weaknesses and take improvement measures. For example, if a student gets a low score in a subject, he or she may spend more time studying the subject. Similarly, if a company's ranking in the market drops, it may re-examine its strategy and operating model.

4. In order to find ways to improve competitiveness. Motivation and promotion: Ranking can motivate individuals and organizations to pursue better performance and results. For example, if students know that their grades are low, they may study harder to get better grades. Similarly, if a company realizes that its position in the market is unstable, it may take measures to improve its competitiveness.

Ranking is of great significance in many fields, which can provide useful reference information for people, help individuals and organizations to evaluate their strengths and weaknesses, and find new opportunities and challenges.