1. Preliminaries.
2. Heterotic string and motivations for large volume compactifications;
2.1 Gauge coupling unification; 2.2 Supersymmetry breaking by
compactification.
3. M-theory on S^1/Z_2 \times Calabi-Yau.
4. Type I/I' string theory and D-branes;
4.1 Low-scale strings and extra-large transverse dimensions; 4.2 Relation
type I/I' -- heterotic.
5. Type II theories;
5.1 Low-scale IIA strings and tiny coupling; 5.2 Large dimensions in type
IIB; 5.3 Relation type II -- heterotic.
6. Theoretical implications;
6.1 U.V./I.R. correspondence; 6.2 Unification ; 6.3 Supersymmetry breaking
and scales hierarchy ; 6.4 Electroweak symmetry breaking in TeV-scale strings.
7. Scenarios for studies of experimental constraints.
8. Extra-dimensions along the world brane: KK excitations of gauge bosons;
8.1 Production at hadron colliders; 8.2 High precision data low-energy
bounds; 8.3 One extra dimension for other cases; 8.4 More than one extra
dimension.
9. Extra-dimensions transverse to the brane world: KK excitations of
gravitons;
9.1 Signals from missing energy experiments; 9.2 Gravity modification and
sub-millimeter forces.
10. Dimension-eight operators and limits on the string scale.
11. D-brane Standard Model;
11.1 Hypercharge embedding and the weak angle; 11.2 The fate of U(1)'s and
proton stability.
12. Appendix: Supersymmetry breaking in type I strings;
12.1 Scherk-Schwarz deformations; 12.2 Brane supersymmetry breaking.Comment: 53 pages, Latex, 7 eps-figures, references and acknowledgments added.
Based on lectures given at Centre Emile Borel during the semester
"Supergravity, Superstrings and M-theory", at the "LNF-INFN Spring School in
Nuclear, Subnuclear and Astropartcle Physics", Frascati, at the Glasgow
"Workshop on Phenomenology of Extra Dimensions", at the "NATO ASI school on
Recent Developments in Particle Physics and Cosmology", Portugal, at the
"38th Course on Theory and Experiment Heading for New Physics", Erice, and at
the "RTN Workshop on the Quantum Structure of Spacetime", Berli
