The definition of a webinar is fairly simple and straightforward.
A webinar is simply an online seminar or presentation.
The words web (how a webinar is delivered) and seminar (a presentation) were combined to produce the word webinar.
A webinar is presented similar to how you would deliver a topic in-person through a workshop or seminar only it is broadcast online through a computer and the Internet using an online service like GoToWebinar.
Webinar can be used in many different ways (like for online team meetings and one-on-one sales pitches) but primarily it is used to share your computer screen with your participants.
Participants sign up for your webinar just like they would at an in-person workshop, allowing you to track important information about your registrants.
Participants use their computer speakers or call in to a special phone to hear your presentation and log on to your webinar with special free software to see your screen or presentation.