From the contents: 1. Collective behaviour, from particles to fields; 2. Statistical fields; 3. Fluctuations; 4. The scaling hypothesis; 5. Perturbative renormalization group; 6. Lattice systems; 7. Series expansions; 8. Beyond spin waves; 9. Dissipative dynamics; 10. Directed paths in random media; Solutions to selected problems; Index. ukryj opis