There's no such thing as a free lunch. But online surveys get pretty close. You could earn as much as £5 by completing a survey which could take as little as 30 minutes to complete – that's enough to cover a sandwich.
But sites differ widely both in terms of payments and time and effort involved. We list the best online survey sites below, including the average payments, how they are made, and how to go about signing up.
Ipsos, which was formed in 1975, is one of the largest market research firms in the world.
The company has an offshoot website called Ipsos i-Say which offers users the chance to earn vouchers for filling out surveys on "anything from global brands to entertainment and more".