Hi @bfitte and welcome to the Canvas Community. QTI stands for Question and Test Interoperability. It's the standard format that assessments/quizzes are saved in when exported from a learning management system such as Canvas. It's typically a zip file that contains details of the quiz settings, the questions, any images embedded in a question etc. It allows you to export a quiz from one Canvas course into another, or even import a quiz into Canvas that was created in another learning management system such as Blackboard or Moodle.
These pages have information on the export and import functions in Canvas:
How do I export quiz content from a course?
How do I import quizzes from QTI packages?
This discussion post is outdated and has been archived. Please use the Community question forums and official documentation for the most current and accurate information.