New data privacy laws and misuse of consumer data have made 2018 an interesting year for marketers that rely on third-party data. Unlike first-party data that is directly collected by whoever uses it, third-party data is information that is collected by a company that doesn’t have a direct relationship with users, e.g. when marketers purchase demographic data from data resellers.
Source : Are Marketers Using Third-Party Data? – eMarketer Trends, Forecasts & Statistics