Exif infos can be used to rename photos For example, including the photos date and time into the filename helps to keep photos organized.
I use Irfanview to rename the files. My standard format is _-.jpg.
The Canon Powershot G2 and G6 cameras use the E306 (DateTime according to the Exif-specification) variable.
Note: “Replace text (2)” replaces space (not visible) with underline.
The Olympus uD500 cam does not support this variable, but in this case the same info can be found in E36867 (DateTimeOriginal).
If also this variable is missing (or there is no EXIF info at all), the date of the file ($T in Irfanview) can be used instead, but the output format is different.