Best advice, how-tos, insights, detailed tutorials, step-by-step guides,
and free code examples from Ionic community leaders.
The release of Ionic 4 was very important because the framework was completely rebuilt from scratch using standard Web APIs, and each component was packaged as a Web Component.
Also, one of the biggest changes to Ionic 4 was that it became completely agnostic of the base framework. (Previously it was linked to Angular.)
Ionic 5 is currently the latest version of Ionic Framework. It was released on February 2020. The changes of this version compared with Ionic 4 were mainly centered around UI/UX. It's a very solid version that allows to build cross-platform native and web apps.
If you want to start building your first Ionic application using Ionic 5, I strongly recommend checking out this Ionic 5 Template that will save you hundreds of hours of design and development by handling all the boilerplate that normally takes weeks.