The mission statement should guide the actions of the organization, spell out its overall goal, provide a path, and guide decision-making. It provides "the framework or context within which the company's strategies are formulated." It's like a goal for what the company wants to do for the world.
According to Bart Christopher, the commercial mission statement consists of three essential components:
Key market: Who is your target client or customer (generalize if needed)?
Contribution: What product or service do you provide to that client?
Distinction: What makes your product or service unique, so that the client would choose you?