Supersymmetry and the brane-world

We discuss the motivation for the brane-world construction and supersymmetry issues. We introduce a concept of bulk and brane supersymmetry within the framework of five-dimensional supergravity which allows one to formulate the rules for supersymmetry in singular spaces. The original fine-tuning of the Randall-Sundrum brane-world which provides the flatness of the brane is shown to follow from bulk and brane supersymmetry on an S-1/Z(2) orbifold. We comment on possible stringy origin of the brane-world related to D8-branes and O8-planes, which can be viewed as a pair of positive and negative tension domain walls in 10 dimensions.