Surveys can be on many different topics, like your TV-watching habits, your favorite places to eat, what material of sweater you prefer in the fall, etc. Many surveys can take less than 5 minutes to complete, although some take longer (and pay more money). Despite the wide array of topics, the end goal of paid online surveys is usually the same: to get a better idea of what consumers are thinking and how they make decisions.
When brands want to find out what consumers think about their product and services, they turn to market research companies. Market research companies are the ones actually administering the surveys on behalf of the corporations looking for data/feedback. Think of online surveys as a type of focus group, except in this case, everything is done online.