Why are pricing decisions important? factor influencing revenue and profit?  element in the marketing mix?

Why are pricing decisions important? factor influencing revenue and profit?
element in the marketing mix?
What if the manufacturer and the retailer are not the same entity?
What does the price mean for the relationships between manufacturer – retailer – buyer?

What is “price”?

What about margins?…

What about the margin/ markup? How do we know what is the maximum margin we can put on our prices based on the costs we incur?