In data publishing, the owner delegates the role of satisfying user queries to a third-party publisher. As the servers of
the publisher may be untrusted or susceptible to attacks, we cannot assume that they would always process queries correctly,
hence there is a need for users to authenticate their query answers. This book introduces various notions that the research
community has studied for defining the correctness of a query answer. In particular, it is important to guarantee the completeness,
authenticity and minimality of the answer, as well as its freshness. We present authentication mechanisms for a wide variety
of queries in the context of relational and spatial databases, text retrieval, and data streams. We also explain the cryptographic
protocols from which the authentication mechanisms derive their security properties.