This plugin will perform a number of checks on your WordPress installation to detect common configuration errors and known issues, and also allows plugins and themes to add their own checks.
The debug section, which allows you to gather information about your WordPress and server configuration that you may easily share with support representatives for themes, plugins or on the official WordPress.org support forums.
Troubleshooting allows you to have a clean WordPress session, where all plugins are disabled, and a default theme is used, but only for your user until you disable it or log out.
The Tools section allows you to check that WordPress files have not been tampered with, that emails can be sent, and if your plugins are compatible with any PHP version updates in the future.
For a more extensive example of how to efficiently use the Health Check plugin, check out the WordPress.org support team handbook page about this plugin.
Feedback is welcome both through the WordPress.org forums, the GitHub project page, or on Slack in either #forums or #core-site-health.