1. Intruduction 2. About logarithms 2-1 What is exponent? 2-2 What is logarithm? 2-3 Various logarithms due to base difference 2-4 Specific logarithmic value 3. What is decibels? 3-1 Definition of decibels 3-2 Specific decibel value 3-3 Decibel representing absolute value 3-4 Advantages of using dB 3-5 Decibel (dB) and percent (%) 4. Decibels in various fields 4-1 Electrical/communication system 4-2 Acoustic system 4-3 Vibration system 5. Calculation of decibel value Reference