  I begin these three lectures by describing some of the useful things that we
have learned about large-N gauge theories using lattice simulations. For
example that the theory is confining in that limit, that for many quantities
SU(3) is close to SU(oo), and that this includes the strongly coupled gluon
plasma just above Tc, thus providing some of the justification needed to make
use of gauge-gravity duality in analysing QCD at RHIC/LHC temperatures. I then
turn, in a more detailed discussion, to recent progress on the problem of what
effective string theory describes confining flux tubes. I describe lattice
calculations of the energy spectrum of closed loops of confining flux, and some
dramatic analytic progress in extending the `universal Luscher correction' to
terms that are of higher order in 1/l, where l is the length of the string.
Both approaches point increasingly to the Nambu-Goto free string theory as
being the appropriate starting point for describing string-like degrees of
freedom in SU(N) gauge theories.
