The Giant's Cause...

2004… Most columns are straight with parallel sides and diameters from a few centimeters to 3 m. Some columns are curved and vary in width. Columns can reach heights of 30 m. …

… Most columns tend to have 5 or 6 sides but have as few as 3 and as many as 7 sides.
1940s photo postcard of the Wishing Chair, Giants Causeway. 

The columns may form sets. Straight, regular columns are called colonnade. Irregular, fractures columns are called entablature.
From Spry (1962).