Black Hat SEO - Techniques used to increases a site or page's rank in search engines through means that violate the search engines' terms of service. These should not be exercised at all if you want to stay above board with Google and other search engines:
stuffing keywords everywhere on the website
Pages with malware, viruses
Links manipulation and paid links
Google and other search engines may ban your website for the use of Black Hat SEO.
White Hat SEO - improves your search rankings on a search engine results page (SERP) while maintaining the integrity of your website and staying within the search engines' terms of service.
Some of the techniques include:
Fast loading times
Mobile responsive website
Good Meta tags, Keywords, and H1 heading
Good user experience design for more customer satisfaction
Proper Link building strategies