Does anyone know the more popular electronic components

As a result of the job needs，recently involved in the electronic industry, especially Ic electronic components, but I do not understand this industry。

I heard there are a few electronic components website，such as

http://www.chinaicmart.com/

http://www.brokerforum.com/

http://www.partinchina.com/

http://www.dzsc.com/

Those supply electronic components distributor offering semiconductors, passives, interconnects, electromechanical, power supplies, test and measurement equipment.