There are a variety of methods to analyze Next-Generation Sequencing (NGS) data. In this series, we have introduced data analysis methods based on the Command Line Interface (CLI) which uses keyboard input. However, there are still many users demanding an analysis method using the mouse input. Here, we introduce the Galaxy, an integrated data analysis environment which is one of the most popular data analysis methods. Galaxy can be categorized as a web tool as it is used via a web browser. However, it is not straightforward to get used to Galaxy, because of its looking and terms, for example, workflows or history management. This paper shows the overview of Galaxy and the basic usage of the public server. Supplementary materials are available at our web site, http://www.iu.a.u-tokyo.ac.jp/~kadota/r_seq.html#about_book_JSLAB.