The theme of this undergraduate thesis is to develop a web application for travel agency and to describe the development of the application in detail. After the introduction, all the technologies used for development of the web application are described. Application is divided into client and server part. First, client technologies such as HTML, CSS and JavaScript are defined with examples of use and description of basic functionalities, tags and ways of defining variables and functions. Next, the PHP programming language used on the server side of the application is described. Variables and functions are explained and supported by code examples. The MySQL database management system and the way to connect to the client part of the application using PHP were defined. The next chapter specifies the user requirements for the application, which can be separated into functional and non-functional. User profiles are explained along with assigned functionalities. Based on the specification of user requirements, system models were defined and created that more closely describe the functionality of the system. All modules in the system and the way of organizing and connecting data in the database are described. In the next chapter, the implementation of the system is defined in such a way that images of all created modules are shown for administrators and users of the system. The modules are corresponding with the requirements specifications and system models. Finally, a conclusion is drawn based on the developed application and the technologies used.