Applying Inventive Principles is the simplest and most powerful technique in TRIZ. Applying these princples can solve any kind of contradiction in the world. They are so easy to use that a learner can start using them even after few hours of training/ practice. Principles are essential for each level of TRIZ worker, whether beginer or expert.

According to TRIZ all inventions are made out of the forty and only forty Inventive Principles. Althuller derived the Inventive Problems from a study on more than thousands and thousands of patents and inventive solutions. Applying these forty Principles can solve any kind of contradiction or inventive problem. Although the principles are derived mainly from the patents of engineering and technical field, they are found to be applicable on other fields (such as software, medical, social etc.) as well. Each principle gives an unique perception of the problem and helps brainstorming on solutions from that angle of perception.

The 40 Principles is one of the earliest technique of TRIZ. Many difficult problems are solved by simultaneous application of a combination of Principles. Some of the contemporary TRIZ researchers propose to add more principles to the list but so far there is no other popular principle set except Altshuller's original set of 40 principles.

• Simple enumeration of Principles- Using this method you try to apply all principles one after the other. If principle seem to be useful in the context, select the principle and proceed further. The advantage of this method is you are testing the applicability of all the principles. Hence, no possibility is left out. If time is not a constraint, then this is the best method. The disadvantage is, one has to scan all 40 principles. This is a time consuming process and there is a possibility of being carried away by some principles which may not be useful.
• Random application method- If you always try to apply the princples in a sequential order, there is possibility that you create a specific mindset and take certain things as granted. If you try to apply them in random (may be looking at a random number table) every time you apply, you think refresh. This method is as time consuming as the above (simple enumeration) method but more effective to eliminate the psychological inertia.
• Formulate a contradiction and use only the selected principles with reference to Altshuller's contradiction matrix- This method is relatively less time consuming and more effective. You will apply only 2 or 4 princples to solve your contradiction, and your contradiction is solved. The disadvantage is, you are confined to only the princples reference by the contradiction matrix. Other principles are ignored, even if they propose effective solutions.
• Formulate both direct and reverse contradictions and apply the princples from the matrix- In this method first you formulate the contradiction, suppose the contradiction is 27x12, then you apply the principles for 27x12 and the principles for 12x27 as well. This is not a regular method, but found to be useful in some cases.
• The best method is a combination of all above. You formulate all contradictions, try with all principles refered by the contradiction matrix, besides try other princples as well. This is definitely more time consuming but definitely most effective.