Industrial music differs from most other music styles in its lack of melodies or vocals. Typical Industrial music pieces are assembled from recorded noises (often captured in industrial environments) and electronically generated sounds. Special effects devices and vocoders are used to additionally alter and distort the original material. Some classics of Industrial music are even completely made of white noise that is rhythmically modulated (a good example is Esplendor Geométrico's track "Sinaya" from their classic album "Sheikh Aljama").

Industrial usually does not have a melody, but in most cases it has a very strong rhythm, though most Industrial tracks are in fact produced without a drumkit of any kind (Winterkälte is one of few exceptions, though they in fact use an electronic drumkit).
Vocal parts are also rarely found in Industrial music, and if a track does have vocals, it will usually be short voice samples (for example from "Industrial movies") or heavily distorted vocals.
Industrial is very powerful music and best consumed at high volumes. Some tracks create images of heavy machinery or construction equipment at work, others remind of the monotony of modern factories dedicated to the mass production of consumer goods. Since there are usually no lyrics, it is often hard to define what the "meaning" of a track is -- if it has a meaning. The message of Industrial music can range from no message at all, over glorification of the achievements of modern industry to critical reflections about mankind's influence on the environment.
Similar to most other music styles, the borderlines between Industrial and related music styles are not sharply defined but often gradual. Industrial has a lot in common with electro-pop, EBM and techno. Often it cannot be strictly decided in which category a band belongs, or whether it belongs more to one category than to the other.
Sometimes even electro-pop bands such as Depeche Mode, Front 242 or Nine Inch Nails are called "industrial". However, this is not the kind of music that machinism.org is about (though, in fact, all those bands have one or two tracks that can indeed be considered industrial; for example "Der Verfluchte Engel" by Front 242 is an industrial classic). Good examples for "real" Industrial projects are Esplendor Geométrico, Sonar, Pan sonic, Marita Schreck, Winterkälte, PAL or De Fabriek.
It is interesting to note that most of the groups or projects that produce "Industrial" as defined above, are based in Europe, with very strong communities in Germany and Belgium. Contributions from the USA and the rest of the world are still pretty rare.