The SEO Pyramid is the basis for all the Search Engine Optimisation work we do for customers at The Marketing Techy.
The foundation for any good SEO is technical SEO. This is what happens on your server and with the code of your website. Any errors or problems here will negate SEO efforts in other places. Google needs to understand the code of your website before anything else.
The second level of good SEO is the on-page SEO. This is things like the URL of the page, title, headings, meta description, image tags and the actual content of the body text on a page. This can all be optimised to tell Google what is important.
Lastly the off-site SEO is what other people and website say about your website, brand or company. Google will pick up these references wether on websites or social. This includes link and anchor text from other sites. This can also have a negative influence on your website if it is on a spammy or bad quality website.
Let me know if you have any questions.