This paper introduces the
notion of squeezing functions on bounded domains and studies some of their
properties. The relation to geometric and analytic structures of bounded domains will
be investigated. Existence of related extremal maps and continuity of squeezing
functions are proved. Holomorphic homogeneous regular domains introduced by Liu,
Sun and Yau are exactly domains whose squeezing functions have positive lower
bounds. Completeness of certain intrinsic metrics and pseudoconvexity of
holomorphic homogeneous regular domains are proved by alternative method. In
the dimension one case, we get a neat description of boundary behavior
of squeezing functions of finitely connected planar domains. This leads to
necessary and sufficient conditions for a finitely connected planar domain
to be a holomorphic homogeneous regular domain. Consequently, we can
recover some important results in complex analysis. For annuli, we obtain
some interesting properties of their squeezing functions. Finally, we present
some examples of bounded domains whose squeezing functions can be given
explicitly.