Manual:$wgUploadPath

Details
The URL of the upload directory, relative to DOCUMENT_ROOT.

Note: $wgEnableUploads is commented out by default. Also remember to set directory permissions.

To enable permission checks on image files, $wgUploadPath can be pointed to the img_auth.php script - see Manual:Image Authorisation for instructions.

''Note: There are other variables which are defined relative to this one. If you redefine this in your LocalSettings.php then all dependent variables including wgUploadDirectory will need redefining also!''