The main concern of this thesis is to analyze the ERP system MS Dynamics AX from a different perspective than is perceived by most general users. This work deals with the description of a programming environment in which the system changes are being developed. Describes the basic technologies it uses and tools to support developers in their everyday work. It also emphasizes the fundamental rules without which any changes in the system are rather counterproductive and would therefore not lead to the desired result. The practical part is focused on a business case of development of a single application. It is a sample example from practice which describes the lifecycle of the application, from the initial definition through the analysis and development, till installation and usage. The thesis is finished by the conclusion which contains a summary of the most important points which should be reader aware of after reading and understanding this thesis.