When you buy land, want to erect a building, want to launch a new product on an unknown market, when planning a vacations far or near, when you want to do an expensive purchase, before putting together a tender, before evaluating offers, when looking for a job advertises, when in need to know the opinion of your website user, e.g., you need a survey. In short: when you start a project, you need a survey to support a study.
A survey provides a solid foundation for planning and decisions that are necessary to make and includes, but is not limited to, the following: