The Media Add New Screen allows you to upload Media (images, videos, files, etc.) for later use in your posts and pages. This screen allows you to both add single items as well as perform bulk uploads, if you wish to add more than one media item to your Media Library. Uploading media from your local computer into the Media Library is quite simple. Two ‘uploader’ methods, Multi-File Uploader and Browser Uploader, are provided. The Multi-File Uploader is the primary method for adding media to the Media Library, but if doesn’t work then click the “Browser Uploader” link to use the Browser Uploader.
As explained above, there are two types of Media Uploaders that are used in WordPress. The first is the Multi-File Uploader. This is considered the preferred method, but if your browser can’t support HTML 5, the Browser Uploader will work.