Column notes group information according to its type and then arrange it in columns. The number of columns depends upon the type of information being dealt with and what it is being used for.
Ideas or headings are listed in the left hand column and details and explanations are listed in the middle column.
The third column is used for critical reflection, i.e. your thoughts on the information collected. You can also use the third column to add notes to yourself, e.g. where you need further evidence.