Mission is an expression of meaning and purpose of the existence of an organization. A statement of why the organization exists, what it wants to do, what it can do. The basic mission of every organization is to provide its customers either a service or sell them or otherwise provide its products.
Why do we need to know a mission in practice?
Mission helps to realize why the organization exists. Why was founded. For all employees, managers is good to know the mission. Sometimes it is good to present to the customers or other interested parties. The mission should not be formulated in general, but specifically. It should be understood by all employees of the organization and ideally all staff should identify with it.
On the most general level, the mission of business organization can be expressed in words of Peter F. Drucker:
“When we want to know what the business really is, we must start from the purpose of its existence. This purpose shall be outside of the business itself. Truly it must lie in society since the organization is a body of the society. There is only one acceptable definition of the purpose of a business: it is to create a customer.”