How can I know which version of Drupal is installed in my server?
For Drupal7
Two ways you can find installed drupal version.for this you have to logged in as admin.
1.Go to Url 'admin/reports/status',on status report page it will show first drupal with its version.
2.Go to Url 'admin/modules',on finding core tab ,we can find drupal contributed modules with 'version'.
For Drupal8
Open drupal\core\lib\Drupal.php in your text editor
you will see something like this (from line 79 to line 84)
open drupal\core\lib\Drupal.php in your text editor
you will see something like this (from line 79 to line 84)
class Drupal {
/**
* The current system version.
*/
const VERSION = '8.2.3';