Is it mandatory to keep images at 72DPI for web design?

Question

I have been designing web banners for more than a year but never considered the DPI.I was using the default 72DPI, but now I want to know is it necessary to create web designs in 72DPI? What if we use more than that, for example 200DPI? I know that more DPI means more quality image and thats why I want to use high DPI, but recently I read somewhere that for web banners we should use 72DPI. I just want to know if it is mandatory and does it affect negatively in any aspect?

Answer 1

Image quality is important however, when it comes to websites you want to make sure the file size is as small as possible so it can load fast but 72 is the default number that I been using for images.