Structural health monitoring, SHM in short, is a relatively new concept, born at the meeting of high in service reliability commandments and optimized maintenance required for highly sensitive products, like aerospace structures, and then extended to all kind of vehicles, nuclear and chemical plants. It is a complex topic that requires, in most of the cases, a multi- and interdisciplinary approach. The paper intends to detail these features and outline the necessity to have a good understanding of all aspects and a good co-operation between all actors involved, in order to make SHM a highly efficient operation, from every point of view.