What is Breadboard ?
A Breadboard or a Test-board, Protoboard or Plug-board is a testing board used for testing of circuits before implementing them permanently on a PCB. It is a simple plastic board which is wired from inside in a particular manner and you can test circuit comprising of resistors, capacitors, IC's and many other pin devices by just plugging it inside the holes provided. Breadboards are reusable, you can do as many implementations as you want. For those who never saw a breadboard before than check out the image below.
A Breadboard has three sections. The right most section and the left most section are same and we will call it as "Power Rails". Our power supply through out the breadboard will be through these buses that's why they are termed as Power Rails. The middle section is were we are going to make all our connections like interfacing of circuits, micro-controllers and other IC's and all that stuff. So these buses are meant for components connections so we will call it as "Components Rails".
Whats inside a Breadboard ?
The image above is the interior look of breadboard. The buses are simple metal strips having a holding mechanism. Whenever you insert any component (resistor, IC, capacitor etc) in it, the holding mechanism grabs the leads of component and the bus get connected to the component. Another thing about breadboard is that if your circuit takes up very large space, then you can also join two breadboards together by inserting the slots into each other provided on the border of the board. So these are all the basics about breadboard