The weekly introductions on this "learnmoodle" course are good examples of a webinar. The term webinar comes from a combination of web and seminar. As in a seminar there is a degree of interaction in a webinar, even if there are teachers/presenters taking a leading position.
Features of a webinar are...
that all participants are online,
there are one or more speakers presenting information
the"audience" can send in feedback or questions in some form and the presenters therefore interact with the audience
Often a webinar is recorded so that those who couldn't take part "live" can still see the webinar. See also "Adobe Connect".
