SEO may generate an adequate return on investment. However, search engines are not paid for organic search traffic, their algorithms change, and there are no guarantees of continued referrals. Due to this lack of guarantees and certainty, a business that relies heavily on search engine traffic can suffer major losses if the search engines stop sending visitors.[59] Search engines can change their algorithms, impacting a website's placement, possibly resulting in a serious loss of traffic. According to Google's CEO, Eric Schmidt, in 2010, Google made over 500 algorithm changes – almost 1.5 per day.[60] It is considered wise business practice for website operators to liberate themselves from dependence on search engine traffic.[61] In addition to accessibility in terms of web crawlers (addressed above), user web accessibility has become increasingly important for SEO.
Website saturation and popularity, or how much presence a website has on search engines, can be analyzed through the number of pages of the site that are indexed by search engines (saturation) and how many backlinks the site has (popularity). It requires pages to contain keywords people are looking for and ensure that they rank high enough in search engine rankings. Most search engines include some form of link popularity in their ranking algorithms. The following are major tools measuring various aspects of saturation and link popularity: Link Popularity, Top 10 Google Analysis, and Marketleap's Link Popularity and Search Engine Saturation.
What's the authority of your website or webpage, or any other page on the internet for that matter where you're attempting to gain visibility? Authority is an important component of trust, and it relies heavily on quality links coming from websites that Google already trusts. Authority largely relates to the off-page optimization discipline of SEO that occurs away from the webpage as opposed to the on-page optimization that occurs directly on the webpage.
Search engine marketing is the practice of marketing a business using paid advertisements that appear on search engine results pages (or SERPs). Advertisers bid on keywords that users of services such as Google and Bing might enter when looking for certain products or services, which gives the advertiser the opportunity for their ads to appear alongside results for those search queries.

There are ten essential types of marketing that can be done online. Some of these can be broken down into organic marketing and others can be categorized as paid marketing. Organic, of course, is the allure of marketing professionals from around the planet. It's free and its unencumbered traffic that simply keeps coming. Paid marketing, on the other hand, is still a very attractive proposition as long as the marketing pays for itself by having the right type of offer that converts.
Probably the most well-known Integrated Vertical Search is  Google’s “Universal Search” –  although all of the major search engines have now adopted similar search formats. This is the practice of incorporating different types of results in the Search Engine Results Pages (SERPs), such as news releases, images, videos, etc., depending on the query.  This was a game changer for SEO when it was first introduced – it became necessary to create and optimize many different types of content because they all show up on SERPs. The term for this comprehensive approach is referred to as Digital Asset Optimization (DAO).