Civil Protection and Civil Defence in the Security System of the Republic of Poland

Everyone knows what engineering is. All that's left is to define systems, and I'm not fool enough to do that.

There is no security on this earth; there is only opportunity.

Some engineering artifacts are most easily analysed, described, or designed as an assembly of simpler parts. Artifacts of this kind are called systems. Some systems have the property that flowing through them are streams of some 'working fluid' (which may be matter, energy, or information), in such a way that the 'working fluid' passes in turn through many parts of the system, which is in consequence termed a sequential (or flow) system. Examples are a chemical plant, an electrical power distribution network, a digital computer, a sewer system. Systems which do not have this property are termed associative systems of which examples are a motor car, an aircraft, or a bridge - - it is with (sequential) systems that the theory of system design has primarily been developed.