It is important to understand the most basic business terminology
Bids - you indicate the price you'd charge to build something or do some work that has been clearly defined by a potential customer.
Estimates - you approximate the price you'd charge to do less-clearly defined work, based on whatever limited information is available.
Proposals - you interpret a potential customer's loosely expressed wishes, specify in detail how you'd meet their needs and how much you'd charge to do it the way you're proposing.
Contracts - a binding agreement between you and a customer, complete with caveats and contingency plans explaining who must do what to hold up their end of the bargain.
Posted via Mobile Device