Web technologies are increasingly relevant to scientists working with data, for both accessing data and creating rich, dynamic, and interactive displays. The XML and JSON data formats are widely used in web services, regular web pages, and JavaScript code, as well as visualization formats such as SVG and KML for Google Earth and Google Maps. In addition, scientists use HTTP and other network protocols to scrape data from web pages, access REST and SOAP web services, and interact with NoSQL databases and text search applications. This book provides a practical, hands-on introduction to these technologies, including high-level functions the authors have developed for data scientists. It describes strategies and approaches for extracting data from HTML, XML, and JSON formats and how to programmatically access data from the web. Along with these general skills, the authors illustrate several applications.