WordPress version 5 was released a month ago on December 6. There have already been some minor upgrades to fix some security issues. If your WordPress site is running any version of WordPress 4, you probably need to upgrade.
Before you upgrade your WordPress site to version 5, you need to take a look at the new page editor, code named “Gutenberg.” If you are comfortable with the way the page editor works, Gutenberg may be a challenge to learn. If on the other hand, you are a more sophisticated developer, Gutenberg should be able to replace some plugins you may have been using to create a more complete editorial palette. My recommendation – look before you leap.
If you decide Gutenberg is not your thing, you can install the plug-in “Classic Editor” and continue to create pages the way you are familiar with. Install Classic Editor before you upgrade to version 5. For me the Classic Editor was the way to go, even though I am planning to learn how the Gutenberg editor works.
This is a major version upgrade, so lots of things can go wrong. There may be issues with some of your plug-ins and themes, so your best practice is to make a full backup of your site pages and database before doing anything else.
You can choose to remain behind, but for security purposes, it is unwise to stop updating your website, so if you remain behind, do so for the shortest time period you can.