GCD file extension - General content descriptor file
What is gcd file? How to open gcd files?
The GCD file extension is also used for a General Content Descriptor format, a file format similar to a JAD format. While a JAD describes a J2ME MIDlet for download, a GCD describes downloads like ringtones and pictures
The GCD's are plain text files and you can create them using any simple text editor like Windows Notepad. If you'd like your phone to download your own picture, then you'll need a GCD file.