  Efforts to construct deeper, realistic, level of physical description, in
which individual systems have, like in classical physics, preexisting
properties revealed by measurements are known as hidden-variable programs.
Demonstrations that a hidden-variable program necessarily requires outcomes of
certain experiments to disagree with the predictions of quantum theory are
called "no-go theorems". The Bell theorem excludes local hidden variable
theories. The Kochen-Specker theorem excludes noncontextual hidden variable
theories. In local hidden-variable theories faster-that-light-influences are
forbidden, thus the results for a given measurement (actual, or just
potentially possible) are independent of the settings of other measurement
devices which are at space-like separation. In noncontextual hidden-variable
theories the predetermined results of a (degenerate) observable are independent
of any other observables that are measured jointly with it. It is a fundamental
doctrine of quantum information science that quantum communication and quantum
computation outperforms their classical counterparts. If this is to be true,
some fundamental quantum characteristics must be behind better-than-classical
performance of information processing tasks. This chapter aims at establishing
connections between certain quantum information protocols and foundational
issues in quantum theory. After a brief discusion of the most common
misinterpretations of Bell's theorem and a discussion of what its real meaning
is, it will be demonstrated how quantum contextuality and violations of local
realism can be used as useful resources in quantum information applications.
