There are two main types of SEO: white hat and black hat. Let's take a look at a few key differences between these two types of SEO.
White Hat SEO
White hat SEO follows Google's guidelines. This type of SEO uses meta tags to give users a brief description of the content, utilizing keywords to help ranking. And when it comes to using keywords in the actual content, there are variations of the chosen target keyword, which helps to provide a better experience for users -- using the right keywords can be the difference between content feeling natural or seeming spammy.
As for links, link building is essential to white hat SEO. If a link is from a high-quality page, the page the link leads to has a better chance of being seen as high-quality as well.
Another key aspect of white hat SEO is providing longer content. With more length, content can go more in-depth and offer more information, which is what users are interested in.
Guest posts are also important with helping to build exposure, links, and authority.
Black Hat SEO
Black hat SEO, while still common, brings a lot of risks. A lot of black hat SEO content is auto-generated; this type of content often includes important keywords but doesn't make sense when being read. Or they utilize keyword stuffing. Or both.
As well as poor keyword strategies, malicious content is often present. This can involve having content or software on a site that doesn’t behave as the user expected; this can be downloads or manipulated content.
Cloaking techniques can make it the content shown in the search engine different to what’s shown in the user's browser. Another common method is creating doorway pages, which impact the index of a search engine where results for particular phrases are shown, but users are sent to a different page.
As you can see, black hat techniques are not a "clean" way to do SEO. This all makes for a very negative user experience and can result in being penalized by search engines, while white hat SEO does everything possible to improve the quality of a site and increase its visibility by adhering to Google's guidelines.