The transistor is made using semiconductor material with three layers. Two types of materials are used. They are P-type and N-type material. The transistor is constructed either by a slice of P-type material is sandwiched between two N-type materials, or a slice of N-type material is sandwiched between two P-type materials.

The first one is called an NPN transistor, and the second one is called a PNP transistor. The inner layer of the transistor is called the base; the other two layers are called the collector and emitter.

Integrated circutes are manufactured by fabricating the hundreds to millions of microscopic transistors. 

Integrated circutes are also called as chips. 

So, integrated circuit are nothing but hundreds to millions of microscopic transistors that are connected to each other.