What is a Common emitter amplifier?

Common emitter amplifier is on in which the emitter terminal is common to both input and output circuit. Following are the some of the characteristic amplifiers of CE amplifier with emitter resistance neglecting the output resistance of amplifier (which accounts for early effect) are

Rin = Rb//(β+1)*(re+Re)

Av = -gm*(Rc//Rl)/(1+gm*Re)

Rout = Rc

Gv = -β*(Rc//Rl) / (Rsig+(β+1)*(re+Re))

Ais = -α*( Rb//(β+1)*(re+Re))/(re+Re).