  We have used Monte Carlo simulations to observe the magnetic behaviour of
Ising thin-films with cubic lattice structures as a function of temperature and
thickness especially in the critical region. The fourth order Binder cumulant
is used to extract critical temperatures, and an extension of finite size
scaling theory for reduced geometry is derived to calculate the critical
exponents. Magnetisation and magnetic susceptibility per spin in each layer are
also investigated. In addition, mean-field calculations are also performed for
comparison. We find that the magnetic behaviour changes from two dimensional to
three dimensional character with increasing thickness of the film. The
crossover of the critical temperature from a two dimensional to a bulk value is
also observed with both the Monte Carlo simulations and the mean-field
analysis. Nevertheless, the simulations have shown that the critical exponents
only vary a little from their two dimensional values. In particular, the
results for films with up to eight layers provide a strong indication of two
dimensional universality.
