n= p= 

μ=  
μ= σ²= 
This is a tool for investigating how good an approximation one distribution is to another.
For example, try plotting Bin(20, 0.4) and then Po(8).
How close are they?
What about Bin(20, 0.1) and Po(2)?
Others to try:
Bin(20, 0.4) and N(8, 4.8)
Bin(20, 0.1) and N(2, 1.8)
Bin(200, 0.1) and N(20, 18)
Po(4) and N(4, 4)
Po(10) and N(10, 10)
etc ...