An SEO friendly website is built in a way that follows strict standards making sure to follow google guidelines. When built from scratch, the end goals of the SEO plan will be built into the website itself. Its a bit like designing a sports car. You use the best components so that its fast. In the same way, the speed of a website is crucial to SEO. Every webpage is built to be speed optimised. This is done by using as little code as possible while making the site a pleasurable experience for the users.