Links- Links from other websites play a key role in determining the ranking of a site in Google and other search engines. The reason being, a link can be seen as a vote of quality from other websites, since website owners are unlikely to link to other sites that are of poor quality.
Content- In addition to looking at links, search engines also analyze the content of a webpage to determine if it would be relevant for any given search query. A large part of SEO is in creating content that is targeted towards the keywords that search engines' users are searching for.
Page structure-Webpages are written in HTML, how the HTML code is structured can impact a search engine’s ability to evaluate a page. Including relevant keywords in the title, URL, and headers of the page and making sure that a site is crawlable are actions that site owners can take to improve the SEO of their site.
Call to action is a marketing term for any design to prompt an immediate response or encourage an immediate sale.