When you take pictures using your digital camera, it usually saves the pictures in the names that do not reflect the date or time. The file names of these pictures generally start with DSC or IMG and end up with a random number, for example, DSC13429.JPG. Fortunately the camera saves the date and time of taking the picture in the EXIF data that is embedded inside the pictures. You can later use this data to rename the picture files based on the original data and time using a freeware software called Exif Rename. Using this tool, you can change the picture name from DSC13429.JPG to 2013-04-03_22-13-26.JPG.
The Exif Rename tool must be installed in Windows before you can start to use it. When you start it for the very first time, it displays a small window where you can choose a user interface language. You can choose from English, Italian, Russian, Spanish and Swedish.
After this the main window opens up. Here you can click on the Open button to select the picture files. You can select one or more JPG files in one go. Then you can select options of whether you want to retain the original file name and append or suffix with date and time. You can also choose to use a word or phrase before or after the date and time. If you do not want to rename the original files, then you can choose to copy them first to another location and then rename them.
As you click on the Go! button, it starts to detect whether the selected files have EXIF data. If the EXIF is not present, then those files cannot be renamed. If it detects the EXIF in a JPG file, then it renames it based on your selected options.
Conclusion: If you want to rename your pictures based on the time and date on which they were taken by your camera, then you can use the free Exif Rename tool. It can detect EXIF data in picture files and renames them quickly adding the date and time to the file names.
You can download Exif Rename tool from http://ceicer.org/exifrename/index_eng.php.