On-Page Optimization refers to strategically placing keywords within your content, titles, URLs, etc. to increase SEO value. As opposed to off-page optimization, on-page optimization is almost entirely controlled by your company, so make sure that your website is as optimized for SEO as possible.
They are actions taken within an actual website to improve its position in search engine results. This is includes internal and external linking strategies, metatags and keyword placement within content.