Pillar candles are a type of molded candle. The wax is rigid enough to burn free-standing (on a heat-resistant plate or pan.) If it is wicked correctly, it should burn evenly and not drip very much wax onto the plate. The most common pillar candles are cylindrical, and come in sizes from 1″ to 4″ and even larger. (At a trade show, I once saw a pillar candle that stood over 3′ tall and was over 12″ in diameter!)
They also come in square, egg-shaped, star-shaped, triangular and other basic shapes.
Other free-standing candles can be made with intricate molds and give amazing detail. While technically these would still be pillars… they’re usually referred to more as “novelty” candles.
Traditional pillars can also be made in varieties like:
Rustic pillar candles
Layered pillar candles
Chunk pillar candles
Ice candle pillars
Source : About.com