After spending months in Beta version, Scratch 3.0 has been finally released as of January 2nd 2019. It brings major changes such as support for tablets and implementation of an HTML, CSS, and JavaScript-based extension system instead of the previously used Flash.
In his blog post announcing Scratch 3.0 Mitch Resnik, leader of the MIT Media Lab wrote:
Scratch has grown beyond our most optimistic expectations. There are more than 30 million registered members on the Scratch website, and every month 1 million new people join (most of them ages 8-16). Every day, Scratch community members create more than 200,000 new stories, games, animations and other projects on the site. And the Scratch block-based approach to coding has become the de facto standard for introducing students to coding.
The initial version, Scratch 1 was desktop-only, Scratch 2.0. released in 2013 had both an offline and online editor. Scratch 3.0 was first announced in 2016 and went through several alpha and preview versions before August 1st 2018 when the beta was released. Scratch 3.0 runs on the desktop using Chrome, Firefox, Edge and Safari – but not Internet Explorer. On tablets it needs Mobile Chrome or Mobile Safari. The Scratch Desktop, which requires Windows 10+ or macOS 10.13+, is provided as an offline editor.
The new version of Scratch includes dozens of new sprites and backgrounds, a totally new sound editor, and many new programming blocks. Although no coding blocks have been removed in the new version some have moved or changed and the blocks themselves have increased in size to work on touch devices.
New blocks include:
- New “sound effect” blocks
- New operators that make it easier to work with text (strings)
- New pen blocks, including support for transparency
- New glide block to move easily to a sprite (or random point)
- Many new capabilities through “Scratch Extensions”
Extensions in Scratch are collections of extra blocks in the Scratch editor. In the new version there are extensions that enable you to program physical devices (such as micro:bit and LEGO robotics kits) and to translate text, using Google Translate, within your Scratch projects.
In his blog post Mitch Resnik explains how the new generation version of Scratch aims to do more than just introduce coding:
But just engaging more students in coding has never been our top priority. Rather, our educational mission is to engage students in thinking creatively, reasoning systematically and working collaboratively—essential skills for everyone in today’s society. From the beginning, we integrated Scratch coding activities into an online community, so that students can provide feedback, inspiration and encouragement to one another. And we took a project-oriented approach so that students can learn to express themselves creatively and develop their creative capacities.
Over the past decade, we’ve found that it’s much easier to spread the technology of Scratch than the educational ideas underlying it. So in developing our newest generation of Scratch, we’ve put special emphasis on supporting the interest-driven, project-based, creativity-enhancing activities that are at the heart of our educational approach. 
FAQ about Scratch 3.0 here: https://scratch.mit.edu/info/faq#scratch3
Online Editor: https://scratch.mit.edu/projects/editor/
Download Desktop Version: https://scratch.mit.edu/download