How is pricebook associated with opportunity in Salesforce?

Opportunity
Opportunity object stores data of potential sales and pending sales.
One opportunity can only have one pricebook.
One opportunity can contain one or many line items.
Pricebook
Pricebook object store a list of products and services for sale.
A pricebook can be used in one or more different opportunities.
A pricebook has one or more different price entries.