Arc Floor Lamps
An arching floor lamp
Arc or "arch" floor lamps feature a long arching arm which reaches over furniture and lowers the light in front of the furniture. Usually the base of the lamp sits behind a sofa/couch or chair or other furniture. The arm comes up behind the furniture and arches over and down. Usually a lamp head or LED light will then illuminate at the end of the arm, sometimes covered with a shade.
Modern arc floor lamps
An arc lamp tends to be quite a modern looking floor lamp design because the long arm tends to be thin and simple in style. It provides a more minimalist style of lighting and is well suited to a modern living room. They can be used also for example over a bed but are most often found arcing over a couch or seating area.
With the advent of LED lighting, an led arch lamp may also do away with a hefty lamp head in favor of placing the led lights in-line in the arm of the lamp itself. A modern arching lamp is well suited to a contemporary home.
An arched standing lamp
With it "up and over" style, an arch-style tall lamp is likely to be quite noticed in a room. It will sit out of the way of foot traffic, but still takes up quite a lot of space. Usually it used over a seating area otherwise it would take up too much space in a room, and is not designed to be walked under.
An arc lamp may also be adjustable in some way allowing you to either pivot or tilt the lamp head, or to change where the lamp is positioned. This can also be useful for moving the lamp out of the way when not in use.
Tall arc lamps are usually not as tall as a typical vertical standing floor lamp, and their relaxed pose can add to the modern yet casual feel of a living room.