Your list's columns

Settings → List columns are the extra details you keep about each lead: industry, city, birthday, plan. An import adds a column for every one it doesn't know, so nothing in your file is lost.

• Each column becomes a merge tag, like {{industry}}.
• Segments can choose people by a column (is, contains, is empty).
• A date column can start an automation, like a birthday email.
• Renaming a column keeps its tag; removing one removes its values from every lead.