Not to be confused with the great American memo book company called Field Notes, but instead the term Fieldnotes. It's the idea of a tool that every marketer should adopt.
Here is the definition:
Fieldnotes refer to qualitative notes recorded by scientists or researchers in the course of field research, during or after their observation of a specific phenomenon they are studying. The notes are intended to be read as evidence that gives meaning and aids in the understanding of the phenomenon.
These are the types of notes that marketers should be taking on a continuous basis. Notes about what a customer said, where they said it, when they said it and who they said it to - along with all the things that they didn't say. The more detailed the notes the better because the ultimate goal is to get closer to the understanding the true nature of the customer - from there you have a chance to build a real marketing experience that truly resonates with that customer at a fundamental level.