Pi and sigma bonds?

i need these explained in simple language

 1.A sigma bond is just a single bond.

2.When you have a double bond, you have 1 sigma bond and 1 pi bond.

3.When you have triple bond, you have 1 sigma bond and 2 pi bonds. 

How does pi bonds arises?
First of all, only period 2 elements form pi bonds. This is due to the fact that period 2 elements are small in size and therfore form short bonds. Due to these short bonds, when 2 atoms like Carbon and Oxygen form a sigma bond, they are so close together, that an energy level(orbital) of carbon overlaps with an energy level(orbital) of oxygen. This forms a pi bond where electrons ''orbit'' around.

Plz APPROVE!