Document Size increases on changing from Higher PPI to Lower PPI || What exactly is PPI - Pixels Per Inch in a Photograph

First of all, Let's understand what PPI is ? PPI stands for 'Pixels per Inch', which has literal meaning that when a image is constructed, how many pixels are places in one inch region of that photograph. More the pixels, better is quality and increase the chances of using this image for various purposes. This is one of the reason that many times people reduce the PPI for a photograph before posting on websites or blogs, so that others can't use them for any commercial purpose. Let's continue this discussion from here...