In 1998, two graduate students at Stanford University, Larry Page and Sergey Brin, developed "Backrub", a search engine that relied on a mathematical algorithm to rate the prominence of web pages. The number calculated by the algorithm, PageRank, is a function of the quantity and strength of inbound links.[22] PageRank estimates the likelihood that a given page will be reached by a web user who randomly surfs the web, and follows links from one page to another. In effect, this means that some links are stronger than others, as a higher PageRank page is more likely to be reached by the random web surfer.
There are three types of crawling, all of which provide useful data. Internet-wide crawlers are for large-scale link indexing. It's a complicated and often expensive process but, as with social listening, the goal is for SEO experts, business analysts, and entrepreneurs to be able to map how websites link to one another and extrapolate larger SEO trends and growth opportunities. Crawling tools generally do this with automated bots continuously scanning the web. As is the case with most of these SEO tools, many businesses use internal reporting features in tandem with integrated business intelligence (BI) tools to identify even deeper data insights. Ahrefs and Majestic are the two clear leaders in this type of crawling. They have invested more than a decade's worth of time and resources, compiling and indexing millions and billions, respectively, of crawled domains and pages.
Clear view of rankings and postions, site audit tool for quick scan and backlink checker are very usefull. I use it a lot and also use the lead generator to get a free scan for potential clients wich runs automated when they fill in te form. The dashboard gives you a good view of changes in traffic and positions. The marketing plan is i bit simple but it gives you some direction of what to do first on the website and you can also check the boxes when you finished a task wich works very well
Tablet - We consider tablets as devices in their own class, so when we speak of mobile devices, we generally do not include tablets in the definition. Tablets tend to have larger screens, which means that, unless you offer tablet-optimized content, you can assume that users expect to see your site as it would look on a desktop browser rather than on a smartphone browser.

Since heading tags typically make text contained in them larger than normal text on the page, this is a visual cue to users that this text is important and could help them understand something about the type of content underneath the heading text. Multiple heading sizes used in order create a hierarchical structure for your content, making it easier for users to navigate through your document.
The caveat in all of this is that, in one way or another, most of the data and the rules governing what ranks and what doesn't (often on a week-to-week basis) comes from Google. If you know where to find and how to use the free and freemium tools Google provides under the surface—AdWords, Google Analytics, and Google Search Console being the big three—you can do all of this manually. Much of the data that the ongoing position monitoring, keyword research, and crawler tools provide is extracted in one form or another from Google itself. Doing it yourself is a disjointed, meticulous process, but you can piece together all the SEO data you need to come up with an optimization strategy should you be so inclined.
Once you have your keyword list, the next step is actually implementing your targeted keywords into your site’s content. Each page on your site should be targeting a core term, as well as a “basket” of related terms. In his overview of the perfectly optimized page, Rand Fishkin offers a nice visual of what a well (or perfectly) optimized page looks like:
The SERP is the front-end to Google's multi-billion dollar consumer research machine. They know what searchers want. In this data-heavy talk, Rob will teach you how to uncover what Google already knows about what web searchers are looking for. Using this knowledge, you can deliver the right content to the right searchers at the right time, every time.
Ranking refers to the process search engines use to determine where a particular piece of content should appear on a SERP. Search visibility refers to how prominently a piece of content is displayed in search engine results. Highly visible content (usually the content that ranks highest) may appear right at the top of organic search results or even in a featured snippet, while less-visible content may not appear until searchers click to page two and beyond