  I present a discussion of fundamental stellar parameters and their
observational determination in the context of interferometric measurements with
current and future optical/infrared interferometric facilities. Stellar
parameters and the importance of their determination for stellar physics are
discussed. One of the primary uses of interferometry in the field of stellar
physics is the measurement of the intensity profile across the stellar disk,
both as a function of position angle and of wavelength. High-precision
fundamental stellar parameters are also derived by characterizations of binary
and multiple system using interferometric observations. This topic is discussed
in detail elsewhere in these proceedings. Comparison of observed spectrally
dispersed center-to-limb intensity variations with models of stellar
atmospheres and stellar evolution may result in an improved understanding of
key phenomena in stellar astrophysics such as the precise evolutionary effects
on the main sequence, the evolution of metal-poor stars, stellar pulsation,
mass-loss from high-mass main-sequence stars as well as from evolved stars,
circumstellar environments, stellar magnetic activity, stellar rotation, and
convection and turbulent mixing. Examples of already achieved results with
existing interferometric facilities and anticipated improvements during the
VLTI era are described. A science case for a next-generation optical/infrared
interferometric facilities is presented, and the required specifications to
achieve it are given. Finally, important synergy effects with external
facilities in order to reach a more complete picture are discussed.
