of or pertaining to a local rail rapid-transit system using large, single passenger cars, railroad-type signals, and, usually, private rights-of-way.

Light rail is a form of mass transit derived from the streetcar concept with the exception that light rail is fully grade-separated and typically operates in a dedicated right-of-way.

Light rail has been around since the late 20th century and is quickly catching on as an extremely efficient manner to move passengers along a corridor with a cost much cheaper than that of heavy rail systems.

Several cities around the world are now constructing new light rail systems to accomodate future growth patterns and ongoing price increases for road construction/widening.

How many passengers can be transported on a light rail system?
A light rail line can carry as many passengers as an eight-lane freeway but only uses 1/10th of the land that the freeway would take.
Grade separated simply means that the mode of transit (i.e. a light rail vehicle) travels on a dedicated right of way that is not bothered by any other mode of transit.

Right of way simply means that the mode of transit with the right of way does not need to yield to other modes of transit. Think of this as a pedestrian crossing the street, automobiles must yield to the right of way of the pedestrian, the same goes for automobiles yielding to the right of way for light rail vehicles with a right of way.