Little question!

[martita.sugar]

Let’s create a new document with dimensions 500x400 and 72 dpi.

What's 72 DPI??
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[Hannah]

I'm fairly (although not 100%) sure it means dots per inch, and it has to do with the resolution of the image, I believe. If you're doing this in photoshop then you can change it to pixels :)

[martita.sugar]

Oh I see, thankss! =]

[Kati]

Hannah is right. It influence the quality of the picture if you want to print it, since PS is mainly used in print. :)