In a course, the course owner can set up the access configuration in the "Settings"→ "Access" tab so that guests can also access the course.
The following course elements can be seen by guests:
If you want to give a guest a direct access to a course, you can send him the external link for the course. It is important, that the course is activated for guests in the access configuration. The external link can be found on the info page of the course.