  The current goals of the astrobiology community are focused on developing a
framework for the detection of biosignatures, or evidence thereof, on objects
inside and outside of our solar system. A fundamental aspect of understanding
the limits of habitable environments (surface liquid water) and detectable
signatures thereof is the study of where the boundaries of such environments
can occur. Such studies provide the basis for understanding how a once
inhabitable planet might come to be uninhabitable. The archetype of such a
planet is arguably Earth's sibling planet, Venus. Given the need to define the
conditions that can rule out biorelated signatures of exoplanets, Venus
provides a unique opportunity to explore the processes that led to a completely
uninhabitable environment by our current definition of the term. Here we review
the current state of knowledge regarding Venus, particularly in the context of
remote sensing techniques that are being or will be employed in the search for
and characterization of exoplanets. We discuss candidate Venus analogs
identified by the Kepler and TESS exoplanet missions and provide an update to
exoplanet demographics that can be placed in the potential runaway greenhouse
regime where Venus analogs are thought to reside. We list several major
outstanding questions regarding the Venus environment and the relevance of
those questions to understanding the atmospheres and interior structure of
exoplanets. Finally, we outline the path towards a deeper analysis of our
sibling planet and the synergy to exoplanetary science.
