Common emitter configuration is commonly used for amplifications because 1. The common emitter configuration (CE) provides maximum voltage and current gain and hence provides maximum power gain. The other configurations provide either high current gain or voltage gain but not both for a BJT. 2. It has suitable bandwidth and gain while other configurations only have bandwidth or gain, but common emitter has both of them. 3. The CE configuration has moderate input& output resistance. Therefore many such stages can be coupled to each other without using any additional impedance matching circuits. Due to this automatic impedance matching maximum power transfer will take place from one stage to other.