On Page Factors

Which are the main on page factors in SEO?

All onpage factors are important in SEO.Mainly

-Meta Tags
-Header Tags
-Robots.Txt
-Sitemaps
-Alt Txt
-Content

Title tags
Heading tags
Anchor texts
CMC
Alt Tags

Good schema markup (if your talking local)

“It’s content and links pointing to your site.”

https://searchenginewatch.com/2016/03/24/google-reveals-its-three-most-important-ranking-signals

http://www.localleadprovider.com

Search engine optimization (SEO) is an continous ongoing mechanism which one performs to get better visibility to the web or search engines.

In simple terms to make a website work in such a way that it is communicable to the Search engines and human.

there are various factors that constitues the SEO as a whole.

1] On-page SEO [Factors within the website]
-Site Structure
-Header tags
-Content writing
-Interlinking of the website
-Title
-Meta Descirption
-Keyword density
-LSI (semantics)
-Images
-Pageload time
-robots.txt
-sitemap
-Broken link
-Source code

this are the general things an SEO keeps in mind and work on while doing an on-page and it is just 1 part.
apart from this there are other and most important factor least to say is LINK BUILDING.

hope this helps.

Title tag
Description
keywords
body tags
meta tags
image seo
internal linking