The main feature of Six Sigma system is step-by-step technique, successively used during development of any project - define, measure, analyze, improve, control - or DMAIC.
Consecutive moving through five phases of each project allows obtaining actual results in practice. At each phase of a project specific goals are defined and achieved and related tools are used.
The main goals of each phase are:

Define - defining goals, problems and main stages of existing project, defining customer key demands and most important process factors that need to be improved.

Measure - measuring process effectiveness and putting goal to improve a process, collecting and formalizing data for analysis.

Analyze - detecting root causes of examined defects, analyzing data to establish statistical relation between input and output data of the process, defining parameters for improvements.

Improve - developing solutions to eliminate the detected root causes of defects and implementing new solutions into the process.

Control - establishing an effective control and correction system to ensure an effectiveness of implemented improvements.