User Interviews / Focus Groups.

A panel of people discussing a specific topic or question. Teaches about the users’ feelings, opinions and even language. Useful when the target audience is new or unknown for the team.

How to Conduct User InterviewsInteraction Design Foundation
User Interviews – The Beginner’s GuideThe UX ReviewAugust 15th, 2013
How to Fix the 5 Most Common Mistakes with Focus GroupsUX MagazineMay 13th, 2011
Focus groups - how to run themWebcredibleJune 1st, 2006
The Use and Misuse of Focus GroupsNielsen Norman GroupJanuary 1st, 1997