The optimization of page elements such as page title, meta description, heading tags or images is critical when it comes to search engine optimization. Search engines look at those elements to evaluate the relevancy of a webpage for a specific topic.
Duplicate content refers to identical (or nearly identical) content that appears on websites under more than one URL and present major SEO issues. There are different types of duplication and therefore different ways to resolve it.
The Knowledge Graph is a body of data displayed in Google's result pages and sourced from a variety of trusted sources on the internet: Wikipedia, Wikidata, The CIA World Factbook, etc.