One of the coolest new feature of Sharepoint 2013 is drag&drop functionality when uploading a file from your computer to a sharepoint library. But this has some limitations. Html 5 capable browser has this feature by default so if you have internet explorer 10 you can use it by default. But if you are using ie 8.x or 9.x you do not have this functionality by default. You need an activex control named SharePoint DragUpload Control. In order to have this add on you need to install Office 2013 or installing sharepoint designer 2013 also does the job for you. So if we summarize these browsers
- Internet Explorer 10
- Internet Explorer 9 with Office 2013 or Sharepoint Designer 2013 installed
- Internet Explorer 8 with Office 2013 or Sharepoint Designer 2013 installed
- FireFox 3.5 (or later)
- Chrome and Safari 5.x (or later)
will do the job for you.