In the last post, I mentioned blocks a fair bit, but maybe didn't explain blocks well enough. WordPress has an FAQ which describes blocks:
What are "blocks" and why are we using them?
The current WordPress editor is an open text window—it’s always been a wonderful blank canvas for writing, but when it comes to building posts and pages with images, multimedia, embedded content from social media, polls, and other elements, it required a mix of different approaches that were not always intuitive:
- Media library/HTML for images, multimedia and approved files.
- Pasted links for embeds.
- Shortcodes for specialized assets from plugins.
- Featured images for the image at the top of a post or page.
- Excerpts for subheadings.
- Widgets for content on the side of a page.
- As we thought about these uses and how to make them obvious and consistent, we began to embrace the concept of “blocks.” All of the above items could be blocks: easy to search and understand, and easy to dynamically shift around the page. The block concept is very powerful, and if designed thoughtfully, can offer an outstanding editing and publishing experience.
Basically, every section of a post is a block; headings, paragraphs, images, lists, galleries are all separate blocks. WordPress also recommend that all meta field and shortcodes are upgraded to blocks (this last is more one for plugin developers).
What you're likely to have is less plugins providing blocks.