Lately, I've heard a lot about Angular's new rendering engine - Ivy. I familiar with the term 'Rendering Engine' in context of Browsers and Photoshop. Both of those rendering engines are responsible for 'drawing' the image on the screen. But, I don't really sure what does this Ivy engine renders?
The Ivy rendering engine is responsible for taking you instruction ( templates ) and bringing something into the screen and doing that in an efficient way, it's also responsible for wiring up change detection so all the heavy lifting DOM updates, that's all done by the internal rendering engine, this engine has been updated many times by Angular team and you're not seeing those changes so these updates won't effect the way you write you application, as well as this engine drastically shrinks the bundles hence you'll build way smaller angular apps without adjusting your code.
As i know it's not yet ready for production, there're some missing parts and if you want to build complex or mission critical application you might not fully migrate to Ivy.
See here for more info.