Challenges in Web Search Engines Monika R. Henzinger Rajeev Motwani* Craig Silverstein Google Inc. Department of Computer Science Google Inc. 2400 Bayshore Parkway Stanford University 2400 Bayshore Parkway Mountain View, CA 94043 Stanford, CA 94305 Mountain View, CA 94043
[email protected] [email protected] [email protected] Abstract or a combination thereof. There are web ranking optimiza• tion services which, for a fee, claim to place a given web site This article presents a high-level discussion of highly on a given search engine. some problems that are unique to web search en• Unfortunately, spamming has become so prevalent that ev• gines. The goal is to raise awareness and stimulate ery commercial search engine has had to take measures to research in these areas. identify and remove spam. Without such measures, the qual• ity of the rankings suffers severely. Traditional research in information retrieval has not had to 1 Introduction deal with this problem of "malicious" content in the corpora. Quite certainly, this problem is not present in the benchmark Web search engines are faced with a number of difficult prob• document collections used by researchers in the past; indeed, lems in maintaining or enhancing the quality of their perfor• those collections consist exclusively of high-quality content mance. These problems are either unique to this domain, or such as newspaper or scientific articles. Similarly, the spam novel variants of problems that have been studied in the liter• problem is not present in the context of intranets, the web that ature. Our goal in writing this article is to raise awareness of exists within a corporation.