WordPress is not only the most popular content management system but is also one of the most targetted software. Websites powered by the old/latest version of the WP CMS or outdated/poorly designed plugins/themes are targetted by brute force attacks or the
One of the best things you can do to keep your WP site safe is to use the latest edition of the WP CMS. A new version of WP fixes the issues/bugs that were found in the previous installation.
To know whether you're running the latest version of WP or you'll have to either see the updates section of the WP dashboard or see the source code or use the WP Version Checker tool of Crawlcenter.
The easiest way to check the WP version without logging in to the WP dashboard is to use this tool. The tool will display the WordPress version you're using when you enter the URL of a site in the textbox and then click the "Submit" button.
Note: If the site is using an HTML, CSS minifier plugin, or has been configured to hide the WP edition, the tool won't display its WordPress version.
Also see: WordPress Theme and Plugin detector