What characteristic makes laser light different from ordinary light?

Laser light is characterized by its coherence, which means that the light waves emitted have a consistent phase relationship and a single wavelength. This coherence allows lasers to produce highly focused beams of light that can travel long distances with minimal spreading. Unlike ordinary light, which is typically emitted from many sources and composed of multiple wavelengths resulting in a mix of colors and a more chaotic wavefront, laser light maintains its parallel and uniform nature over significant distances.

This coherence is essential for many laser applications, such as in communications or medical procedures, where precise targeting and minimal dispersion are required. The other characteristics mentioned in the options do not accurately describe the distinguishing feature of laser light: it is not divergent like typical light sources, it can be polarized, but that is not unique to lasers, and it is very specific in color due to the single wavelength emission. Thus, the defining characteristic of laser light is its coherence.