Design Issues in Web Crawlers and Review of Parallel Crawlers

With the increase in size of web, search engine depends upon the Web Crawler to download and build index of million/billion of pages for efficient information retrieval when user interact through search interface. This paper will include the definition of Web Crawler, criteria on the basis of which various types of crawler are defined [4] and some common issues with the design of crawler, parallel crawler, its issues and comparison of solutions provided by researchers.