The purpose of a column is to inform, interpret, and critique events for readers. A good columnist explains the background and consequences of news, determines if events are isolated or part of patterns, and how events may affect readers. They also assess different perspectives from society. A columnist should write well, be original, observe keenly, think logically, have a wide background, and be resourceful and fair. There are different types of columns, including text, number, date/time, and location columns for different kinds of data.