Statistical surveys are general methods to gather quantitative information about a particular population. "Population" here does not necessarily mean a set of human beings, but may consist of other type of units - firms, households, universities, hospitals, etc.
While there are types and forms of surveys, they have one common feature: any survey normally involves administering questions to individuals. Examples of surveys are opinion polls, country population census, telephone interviews of personal consumption details and preferences, etc.
Surveys are widely used in market research, political polling, social research, medicine, and monitoring customer and stakeholder opinions and perceptions.