What things are significant in organically ranking a website?

Basically there are various things that are being employed for organically ranking a website which can be classified in 3 distinct categories:
Website content: It must be quality and unique content as well as most be well optimized and well structured.
Website structure: This includes TAGS, clear navigation, ensuring usability, validation of HTML errors and miscellaneous.
Backlinks: You can create a link to anywhere but prior to this it is obvious to ensure for relevant site and healthy link.