Breadboard

Breadboard is a base for constructing electronic circuits. Its is used for testing the circuit i.e it used for building prototype of a circuit. It consists of plastic block with holes and nickel alloy strips under these holes. Breadboard is shown below:

The connection inside the breadboard is shown below:

Black lines shows the way in which nickel strips are placed inside. These strips acts as wires. The electronic componets(like resistor, led, capacitor, wires etc) are inserted in these holes.
When the prototype of the circuit gives the desired result, it is then tranferred to PCB(Printed Circuit Board), which is a permanent one.