You've long had a variety of ways to create and discover new Arduino projects, and now you have an official means with Arduino Create. Arduino Create is a one-stop site to browse various Arduino projects, dig through the help forums, look for Arduino products and even create your own projects with the web-based integrated development environments (IDE).
Like the desktop apps, the web editor allows you to write or import code, then send it right over to your Arduino. Beyond that, you can look up examples, or browse other projects for clues while you're writing your own. It's also easy to integrate your Arduino projects into various online services using the Arduino Cloud, which should make working on web-connected Arduino projects a heck of a lot easier. It's a nice step to integrating everything you need in one place, so if you're a fan of Arduino, it's worth playing around with.