I have been studying about inverters for a while. In the book that I was reading, inverters have been explained according to the type of load connected to the drain of the driving transistors ie. resistive load, e-type nMOS load and d-type NMOS load. In both of the above circuits, if a low input voltage is fed to the gate of the driving transistor the o/p will be high because current does not pass through the load or driving transistor and the o/p is simply Vdd.
When the input voltage is high current passes through the load and driving transistor and a low o/p is obtained because minimal voltage drop occurs in this case. In neither of the above cases does having a load seems to be of any benefit.The loads seem to be simply contributing to power dissipation during linear mode operation and area . Why then are they connected in the first place?