The new app is free, allowing broadcasters to stream live video not just to other Periscope users, but also to Twitter - with just the press of a button. If you don't want your broadcasts to be public, you can choose to only share them with specific people. As viewers, Periscope users can browse live or recent broadcasts, send messages to broadcasters, and "tap the screen to send hearts."
Overall, Periscope aims to deliver "a visual pulse of what’s happening right now," and we'll likely see very interesting broadcasts being made available via the service.
Twitter bought Periscope this year, reportedly paying close to $100 million for it. This is Twitter's second major purchase when it comes to video-related services, after Vine (which was acquired by the company back in 2012 for around $30 million).
Do you think you'll be using Periscope (either as a broadcaster, or a viewer)?
Twitter's Periscope app for iOS
sources: Twitter, iTunes