ExifTool is a command-line application for reading, writing and editing metadata. ExifToolGUI is essentially ExifTool but with a user-friendly interface which has the ability to view all metadata, edit the most frequently used metadata and modify files using batch-mode.
2014 update: The ExifToolGUI interface has changed considerably since I wrote this post. If you’re looking for your available GPS options here, see ExifToolGUI for Windows v5.xx. Frankly, I find it much simpler to use GeoSetter which is also based on Phil Harvey’s ExifTool.
ExifTool is really a misnomer because as well as giving you a view of the EXIF information it also allows you to create and edit IPTC and XMP data.
In order to use ExifToolGUI, follow the simple instructions below:
Unzip both folders. In exiftool, rename exiftool(-k).exe to exiftool.exe, then move it to the exiftoolgui folder. Start the program by clicking on ExifToolGui.exe, browse to a photo folder and you should have something similar to this.
If you want to add GPS co-ordinates, click on the EXIF button, then the caret beneath it. On the next screen click the ‘Various’ tab.
Notice the note at the bottom. Go back to the main screen and click on Options/Show Exif:GPS in decimal degrees. Since co-ordinates come from Google Maps and Bing Maps in decimal format, that will save you the bother of having to convert it yourself. If you need ideas on how to find the co-ordinates, see Writing & Reading GPS.
You can also use ExifToolGUI in batch mode by selecting more than one photo.
When ExifToolGUI writes new data to your photo it does it to a copy and renames the original to ‘original’. This is a thoughtful addition by the programmer. Just in case. You can check your work in XnView and see if the precaution is warranted.
By the way, this is portable software. Have ExifToolGUI, can travel.