Of electric energy, electric power, current and voltage, etc., are the number of the most important electrical and, in addition, the resistance is not a disregard. A circuit or a set equipped with its own characteristics, such as size, shape and material will affect the amount of current. Some obstacle to the current effect may be called resistance.
 
Material charge activities can be subject to encounter resistance similar to mechanical friction. This resistance is the cause collisions between the electrons and the lattice atom or impurity atoms, and this situation causes the electrical energy is converted into heat. Any circuit or installation, often with fever and electric power-consuming. Resistance fever and electric power-consuming, not completely useless, depending on their ability to effectively. Some of the circuit is the the application resistance characteristics as power, for example, we can apply the heater heat; What, then transistor fever Fei-wu people required energy waste.
The resistor can be used to limit the amount of current can also be used to adjust the voltage, there are some other function, specially manufactured appliances known as resistor used for these tasks.