In this article, the author is trying (1) to know more about the Internet industry, theoretically and practically, (2) to know the strengths and weaknesses of Internet companies with different business models, and the criteria that can be used to tell a winner from a would-be loser, and (3) to arrive fundamental approaches that could be used or that would be suitable to the valuation of a given Internet stock. They are mainly because the law of increasing return, first mover advantage, brand name advantage and model consolidation that make the competitiveness of leading Internet companies increase continually, and make it harder and harder to survive for new entrants. The author compares different valuation models including dividend discount model, discount free cash flow method, adjusted discount free cash flow method, EVA method, P/S, P/B, P/E multiples, and other non-financial multiples such as page view multiples and unique visitor multiples. Among them, the adjusted discount free cash flow method is the most suitable model to the valuation of Yahoo! and other leading portals that already report positive earnings or can be sure to make money in the near future. Other valuation models cannot be used to the valuation of portals.