  The emphasis in the developmet of theories with more than three spatial
dimensions has recently shifted towards ``brane world'' picture, which assumes
that ordinary matter (with possible exceptions of gravitons and other,
hypothetic, particles which interact very weakly with matter) is trapped to a
three-dimensional submanifold --- brane --- embedded in fundamental
multi-dimensional space. In the brane world scenario, extra dimensions may be
large, and even infinite; they may have effects, directly observable in current
or fothcoming experiments. On the basis of simple field-theoretic models,
various ideas in this direction are exposed at a non-expert level.
