Inhaltsangabe1 Introduction.- 2 Physical Models.- 3 Kinks.- 4 Breathers.- 5 Ground State.- 6 Statistical Mechanics.- 7 Thermalized Dynamics.- 8 Driven Dynamics.- 9 Ratchets.- 10 Finite-Length Chain.- 11 Two-Dimensional Models.- 12 Conclusion.- 13 Historical Remarks.- References.