Search engine optimization (SEO) is the process of improving the quality and quantity of website traffic to a website or a web page from search engines. SEO targets unpaid traffic (known as "natural" or "organic" results) rather than direct traffic or paid traffic. Unpaid traffic may originate from different kinds of searches, including image search, video search, academic search, news search, and industry-specific vertical search engines.
As an Internet marketing strategy, SEO considers how search engines work, the computer-programmed algorithms that dictate search engine behavior, what people search for, the actual search terms or keywords typed into search engines, and which search engines are preferred by their targeted audience. SEO is performed because a website will receive more visitors from a search engine when websites rank higher on the search engine results page (SERP). These visitors can then potentially be converted into customers.
Methods of search engine optimization
Getting indexed
The leading search engines, such as Google, Bing, and Yahoo!, use crawlers to find pages for their algorithmic search results.
Pages that are linked from other search engine-indexed pages do not need to be submitted because they are found automatically.
The Yahoo! Directory and DMOZ, two major directories which closed in 2015 and 2018 respectively, both required manual submission and human editorial review.
Google offers Google Search Console, for which an XML Sitemap feed can be created and submitted for free to ensure that all pages are found, especially pages that are not discoverable by automatically following links in addition to their URL submission console.
Yahoo! formerly operated a paid submission service that guaranteed to crawl for a cost per click; however, this practice was discontinued in 2010.
Search engine crawlers may look at a number of different factors when crawling a site. Not every page is indexed by search engines. The distance of pages from the root directory of a site may also be a factor in whether or not pages get crawled.
Today, most people are searching on Google using a mobile device. In November 2017, Google announced a major change to the way crawling websites and started to make their index mobile-first, which means the mobile version of a given website becomes the starting point for what Google includes in their index.
In May 2020, Google updated the rendering engine of their crawler to be the latest version of Chromium (69 at the time of the announcement). Google indicated that they would regularly update the Chromium rendering engine to the latest version.
In December 2020, Google began updating the User-Agent string of their crawler to reflect the latest Chrome version used by their rendering service. The delay was to allow webmasters time to update their code that responded to particular bot User-Agent strings. Google ran evaluations and felt confident the impact would be minor.
Preventing crawling
To avoid undesirable content in the search indexes, webmasters can instruct spiders not to crawl certain files or directories through the standard robots.txt file in the root directory of the domain.
Additionally, a page can be explicitly excluded from a search engine's database by using a meta tag specific to robots (usually <meta name="robots" content="noindex"> ). When a search engine visits a site, the robots.txt located in the root directory is the first file crawled.
The robots.txt file is then parsed and will instruct the robot as to which pages are not to be crawled. As a search engine crawler may keep a cached copy of this file, it may on occasion crawl pages a webmaster does not wish to crawl.
Pages typically prevented from being crawled include login-specific pages such as shopping carts and user-specific content such as search results from internal searches.
In March 2008, Google warned webmasters that they should prevent indexing of internal search results because those pages are considered search spam.
In 2021, Google sunsetted the standard (and open-sourced their code) and now treats it as a hint not a directive.
To adequately ensure that pages are not indexed, a page-level robot's meta tag should be included.
Increasing prominence
A variety of methods can increase the prominence of a webpage within the search results.
Cross linking between pages of the same website to provide more links to important pages may improve its visibility. Page design makes users trust a site and want to stay once they find it.
When people bounce off a site, it counts against the site and affects its credibility.
Writing content that includes frequently searched keyword phrases so as to be relevant to a wide variety of search queries will tend to increase traffic.
Updating content so as to keep search engines crawling back frequently can give additional weight to a site.
Adding relevant keywords to a web page's metadata, including the title tag and meta description, will tend to improve the relevancy of a site's search listings, thus increasing traffic.
URL canonicalization of web pages accessible via multiple URLs, using the canonical link element or via 301 redirects can help make sure links to different versions of the URL all count towards the page's link popularity score. These are known as incoming links, which point to the URL and can count towards the page link's popularity score, impacting the credibility of a website.
Also, in recent times Google is giving more priority to the below elements for SERP (Search Engine Ranking Position).
• HTTPS version (Secure Site)
• Page Speed
• Structured Data
• Mobile Compatibility
• AMP (Accelerated Mobile Pages)
• BERT
White hat versus black hat techniques
SEO techniques can be classified into two broad categories: techniques that search engine companies recommend as part of good design (white hat), and those techniques of which search engines do not approve (black hat).
Search engines attempt to minimize the effect of the latter, among them spamdexing. Industry commentators have classified these methods and the practitioners who employ them as either white hat SEO or black hat SEO.
White hats tend to produce results that last a long time, whereas black hats anticipate that their sites may eventually be banned either temporarily or permanently once the search engines discover what they are doing.
An SEO technique is considered a white hat if it conforms to the search engines' guidelines and involves no deception. As the search engine guidelines are not written as a series of rules or commandments, this is an important distinction to note.
White hat SEO is not just about following guidelines but is about ensuring that the content a search engine indexes and subsequently ranks is the same content a user will see.
White hat advice is generally summed up as creating content for users, not for search engines, and then making that content easily accessible to the online "spider" algorithms, rather than attempting to trick the algorithm from its intended purpose.
White hat SEO is in many ways similar to web development that promotes accessibility, although the two are not identical.
Black hat SEO attempts to improve rankings in ways that are disapproved of by the search engines or involve deception.
One black hat technique uses hidden text, either as text colored similar to the background, in an invisible div, or positioned off-screen.
Another method gives a different page depending on whether the page is being requested by a human visitor or a search engine, a technique known as cloaking. Another category sometimes used is grey hat SEO.
This is in between the black hat and white hat approaches, where the methods employed avoid the site being penalized but do not act in producing the best content for users. Grey hat SEO is entirely focused on improving search engine rankings.
Search engines may penalize sites they discover using black or grey hat methods, either by reducing their rankings or eliminating their listings from their databases altogether.
Such penalties can be applied either automatically by the search engines' algorithms or by a manual site review.
One example was the February 2007 Google removal of both BMW Germany and Ricoh Germany for the use of deceptive practices. Both companies, however, quickly apologized, fixed the offending pages, and were restored to Google's search engine results page.
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