dpi - how do they affect an image?
I don't know how dpi (dots per inch) affects an image.
When you start a new file in Photoshop you can set the dpi to your liking.
for example you have a square canvas of 1,000px (width and length) setting the dpi to 100 or 300 doesn't show any changes. Does this have an effect on printing somehow?
Hmm ... DPI helps to smoothen pictures .... the higher the DPI the better the result .... normally 300 dpi is good
http://en.wikipedia.org/wiki/Dots_per_inch#DPI_or_PPI_in_digital_image_files