Which meta tags are the most important?

Question

Search Engine Optimization

Apart from charset, description, keywords, which meta tags are important to include in an html document? For SEO and in general for the site? Maybe something from http-equiv or like

<meta name="viewport" content="width=device-width, initial-scale=1.0">

? Are there any established guidelines for this? What do you usually include in a header without fail?

Answer 1

https://github.com/joshbuchea/HEAD