Support for PHP version 5.6 was discontinued at the end of 2018. PHP is one of the main programming codes behind WordPress (and many other website types of websites).
This means that the good people who maintain PHP will no longer be rolling out security updates for older versions. And consequently, plugin and theme developers will start to stop backwards compatibility. Because of this, you may get a warning message that your ‘PHP is outdated’.
The good news is that you should be using PHP 7.2 because there are performance benefits for your website (ie. it will load faster).
Newly purchased hosting plans on a reputable host will already be on version 7.2. But if you have an older website, you can check what version of PHP you are currently using by using the Display PHP Version plugin from the WordPress plugin repository. Simply install the plugin, activate and it will show the PHP version on your dashboard.
You can use the PHP Compatability Checker plugin from the WordPress plugin repository to see if there will be any issues with updating your website PHP version.
An ultimate test is to get your web developer to set up a version of your website on a local server to simulate updating and sort out any issues before the update is done on the live site.
The actual updating of the PHP version can be done through your hosting by logging into your cPanel or Plesk dashboard. Or give your hosting company a call.
Contact Webtree if you require any assistance with upgrading your PHP version.