SEO professionals lump search engine optimization techniques and thought into three categories—on-page optimization, off-page optimization, and conversion. On-page optimization is concerned with all of the text, images, code, words, navigation, structure, and so on that appear on your website—all of the factors you control that appear on-page. Off-page optimization refers to all of the material on the Internet concerning or pointing to your website that does not appear on-page; for the most part, off-page optimization refers to inbound links on third-party websites. Conversion refers to how effective your website is at making users take actions, once they appear on your site. A high-performing website needs all three elements working together.
On-page factors include the following:
The body content—the main text of the page
Title and meta tags
Heading tags (h1, h2, h3)
The quality and complexity of the HTML and CSS code that generates the webpage
The images, their filenames and alt tags
Text attributes such as the use of bold and underline
Outbound links—their number and the anchor text used in each
The use of either dofollow or nofollow attributes on any of the links
The internal navigation and link structure
The size of your files and the speed at which your website loads
The total number of pages on your website
The rate at which you update or add content to your website
But how important are each of these factors? How do we know that one factor is more important than another? The software or programs that Google and the other search engines use to determine rankings are referred to as an algorithm. While the behavior of search engines can sometimes appear remarkably intuitive and almost human, the science underlying a search algorithm is ultimately reduced to complex mathematics.