If this works properly, little icons should appear in front of links to files of various types:

• Link to a PDF stored in my blog:
  Japanese Stilgrass
• Link to a PDF hosted on a different website (because it is too big to upload here!):
  Fluvial Geomorphic Assessment of the South River Watershed, MA
• Link to an Excel document hosted on Box (can’t upload this mime type to blogs):
  Sample Excel Document
  and hosted on webadmin server:
  Sample Excel Document
• Link to a Word document hosted on Google Drive (can’t upload this mime type to blogs):
  Sample Word document
• Link to MP3 audio file:
  Fly Around My Prettly Little Miss
• Link to a (tiny)  MP4
  Writing Video
• And finally, link to a PPTX:
  Analog and Digital Photography Workflows