A webinar (short for web-based seminar) is a presentation, workshop or lecture that is transmitted over the internet. Unlike a webcast which only sends information, a webinar can send and receive information. It's this interactive ability that allows a webinar to facilitate discussions in a way that webcasts can't. Again, because they are interactive, webinars are always live.
A webinar is hosted on the presenting organization's server. The audience clicks on the appropriate web link and opens the webinar session. The webinar can be presented in a variety of ways: a slide show (using Microsoft PowerPoint), text documents, Flash applications, etc. If the webinar includes video components, then downloading a video stream is required. Audio is accessed through the phone, where webinar attendees can ask questions and participate in discussions with the presenter and each other. Other interactive webinar features can include email discussion questions, online voting and collaborative document sharing.