Tracking and kerning are both measured in 1/1000 em, a unit of measure that is relative to the current type size. In a 6‑point font, 1 em equals 6 points; in a 10‑point font, 1 em equals 10 points. Kerning and tracking are strictly proportional to the current type size. (Leading is measured in points.)
InDesign and Illustrator—which both place a strong emphasis on typography—allow you to adjust the default increment amounts in Preferences. Photoshop—primarily an image editing application—does not have the equivalent feature.
Thanks Barb. That's disappointing that photoshop doesn't have a similar feature. Although it's an image editing application I don't think that's the only way Photoshop is used in the marketplace. I hope Adobe recognizes that in the future. I often have to treat typography just like imagery, which is why it would be great to have quick and customizable ways to set type the same way I can with Indesign and Illustrator. Thanks again for your thorough and definitive answer.
I do agree with you that Photoshop is no longer only an image editing application. There’s a lot of overlap between these applications these days. Are you aware you can add images to Illustrator—I wonder If that would be helpful in your workflow?
And you can certainly add this as a Photoshop feature request: