72 or 96 dpi?
To create an image for the Web or for viewing on a monitor, you may use either standard i.e 72 dpi or 96 dpi (Windows).
Actually, unless you're CREATING the image from scratch (or to be saved as a .gif file), you can use just about ANY dpi setting that you feel comfortable with; cause it really doesn't matter!
That's because all graphics for the Web, meant to be viewed on the monitor screen, is resolution blind!!!
That means, the screen is ONLY interested in the pixel measurements of your images, regardless of the resolution.
3 different resolution images
Following 3 images are produced with 3 different resolutions but with the same pixel dimensions:
200 x 203 pixel (10 dpi)
200 x 203 pixel (72 dpi)
200 x 203 pixel (150 dpi)
Verifying image resolutions
To view the image resolutions of each picture above you have to save it to your HDD and open it in your usual Photo / Image Editor and view the properties of each file to verify the resolutions are indeed 10, 72 and 150 dpi.
Also inserting the images above into a blank MS Word document will reveal the 'true' (print) sizes of these pictures.
The resolution (i.e. dpi) is only important when the image is being printed, believe it or not...
I personally use 75 dpi every time I create an image for the web. I am just used to it, I suppose...