Web search engine is a data mining tool designed for collecting information from the World Wide Web and for displaying the relevant information according to user queries. Usually users can use popular search engines like Google, Bing, Yahoo, or Facebook to find the information. However, there are many occasions that we want to implement our own search engine, e.g., (1) we need a built-in search function in our website, and (2) we want to sell space for advertisements in pages that displayed when specific keywords are entered. This book is written to provide search engine software that can serve for such purposes. Because we believe simplicity is an important factor in the code deployment, we keep simplicity in mind when designing the software. We used Python, a popular multiplatform scripting language with simple syntax and comprehensive libraries to implement the search engine. Step-by-step guide to the software installation in Windows and Linux environment is given. In addition, this book also provides concise description about algorithms used in the software.