div with background or img?

I very often use a block (usually a div ) to insert an image onto a page and insert images through the background . I never wondered why I did this, why I used a block to insert images, and not a special img tag. The question may seem silly, but for the purpose of my development I will ask it: Is it reasonable to replace the img tag with a div block with background-image , if yes or no, it’s advisable to answer why