Most companies and testing books use the term unit testing, but its semantics varies widely in different organizations. Lund University researchers launched a survey in a company network to explore this variation. The survey, which involved companies in focus-group discussions and a questionnaire, focused on defining unit testing, discussing its practices, and evaluating a company's strengths and weaknesses. The results indicate a common understanding of unit testing's scope, although the aim and practices vary across companies. Practitioners can use the survey instruments as a baseline for measuring their unit testing practices and to start improvement initiatives.This article is part of a special issue on Software Testing.