For those of you have been using the fast gallery module, i reckon you know what's the purpose of EXIF data. It is primarily being used to display image caption and title display for custom folder thumbnail. You can customize how the EXIF data would be displayed through Fast Gallery setting depicted below:

Meanwhile, the screenshots below are the actual result of using EXIF data:

- Title display for Custom folder thumbnail using EXIF data

- Image caption using EXIF data

There are plenty of EXIF editors available out there for free, personally i would strongly recommended the EXIF Manager, it is simple and easy to use for starter as opposed to other EXIF editors. With EXIF Manager, you can modify information of a picture such as its image description, user comment, artist, and date. Bear in mind, only .JPG picture has the EXIF data.