What is the file extension for photoshop for the blanks following the period in "photoshop,___"? I have an older desktop which includes older photoshop files which I have asked a technician to extract for me. He asks for the extension. I can't

I ned the extension for the photoshop program, that is, the letters following the period as shown by the blanks in this:  "photoshop.____"   I cannot find the extension in my laptop.  The photoshop program is a couple of years old and my files are in a desktop out of use for a couple years.  I brought the desktop to a technician, asking him to extract the photos.  He asks me for the file extension.