Whenever a new file is created, a menu appears asking for general info such as the file name, width and height, type of color, etc. Why is the default set at 72 dpi? Is there any particular significance to having it at 72 or is it just an arbitrary number that will haunt us forever?
It is screen resolution on the Mac*, and is the standard on which fonts were originally, if somewhat loosely, based.
- In the old days when Macs had 9-inch black and white screens, the display literally had 72 pixels per inch. Nowadays, in the brave new world of multi-resolution video displays, that’s a “virtual inch”.
Which, I suppose, is all a way of saying that it is haunting us forever.
72 dpi is the normal resolution for web graphics. It’s the standard, and probably more likely to be used by anyone using photoshop than any other resolution they could have picked out of a hat.
Im using 5.5, it lets you select the resolution.
that’s just the default. use whatever you need to. for web graphics though, stick to lower dpi. imageready 2.0 comes with Photoshop, that ought to help you make some web ready graphics if that’s your concern.
Adobe (and the original Mac resolution) was set to 72dpi because a standard printer’s point is 1/72 of an inch- i.e., 72pt per inch. I mean “printer” as in a typesetting guy, not a computer printer 
Actually, there are about 72.27 points in an inch, but that got rounded to 72 in computer-land. The point was defined to be exactly 0.013837 inces in 1886, by the American Typefounders Association, so it’s not a new standard.
Arjuna34
Arjuna34, say it aint so… I’m not the only former Typesetter still around? I thought we were a dying breed.
It could also depend on if you have an image copied onto the clipboard. If you copy, say, an image that’s 300 dpi and then create a new file, the resolution will show 300 on the pop up menu. So if you’re using images copied off the web, they will all be 72 dpi. It also adjusts the height and width to the image on the clipboard.
Not even one of the only two. Got into the software business by starting out as proofreader in a type shop, then started setting type occasionally on Compugraphic equipment and moved over to the desktop/PostScript side once that began, ultimately leaving to do support for one of our software vendors. Never drove a hot-metal or PhotoType machine though.