As we know natural frequencies plays an important role in various systems/ structures in our life e.g. bridges. These natural frequencies are calculated in CAE by using modal analysis. This book gives a practical approach to get a better understanding of the importance of natural frequencies. For this one case study of the automobile, chassis is discussed in details. In which modal analysis is done with the help of HyperWorks software and CAD modeling is done with NX software. Also, the experimentation is done with FFT analyzer to get a natural frequency of the system. Both results are compared and validated. Using obtained modal analysis results, optimization of the vibration isolator used in the exhaust system of the heavy commercial vehicle is done.