A Webinar is a seminar presented and consumed online, i.e. a web-seminar. This makes educational material and content much more accessible for others by reducing the geographic restrictions. It’s also possible to offer Webinars at a lower price thanks to the lower overhead costs required, which enhances that accessibility.
Being able to share information and education to more people is obviously a positive step forward, although one often-cited drawback of Webinars compared to in-person seminars is that participants can easily be distracted or not held accountable for paying as much attention as they would when in view of the speaker.