SharePoint 2013, introduces a new feature named "Drag & Drop" where you drag multiple files and drop them into Document library directly. There have been cases where this functionality is not working. I will list out the mininmum requirements here to have this functionaliy on your machine.
It depends on the active x control called SharePoint DragUpload Control. It comes up with the following browsers.
- Internet Explorer 8 with Office 2013 or Sharepoint Designer 2013 installed
- Internet Explorer 9 with Office 2013 or Sharepoint Designer 2013 installed
- Internet Explorer 10
- FireFox 3.5 (or later)
- Chrome and Safari 5.x (or later)
Happy Share Pointing :-)