A website consists of more than just HTML files. Most websites have images, animations, additional code and CSS files and it is good practice to store each of these types in a different subdirectory.
Website Root Folder
-----¦-------------images
-----¦-----------------¦----------image1.gif
-----¦-----------------¦----------image2.gif
-----¦-----------------¦----------anotherImage.jpg
-----¦-----------------¦----------original
-----¦-----------------¦--------------¦-------------image1.psd
-----¦-----------------¦--------------¦-------------image2.psd
-----¦-----------------¦--------------¦-------------anotherImage.psd
-----¦---------------css
-----¦-----------------¦----------main.css
-----¦-----------index.html
-----¦-----------splash.html
-----¦-----------contact.html