1. Indexed Search
1.1. Page Ranking
1.1.1. Factors
1.1.1.1. No. of outbound links coming from from other sites to that page or site.
1.1.1.2. Use of keywords, how long the site is available, and traffic to the site or page.
1.1.1.3. Algo to detremine Page Rank is trade secret.
1.1.1.3.1. Based on these results google offers what is called Search Engine Results Page(SERP).
1.1.1.3.2. Which is then parsed for its keywords.
1.1.1.4. Google is always tweaking the algorithm to prevent Search Engine Optimization (SEO) strategies from gaming the system.
1.2. Offers
1.2.1. Does not
1.2.1.1. Google does not search all sites.
1.2.1.2. Any site that is not the target of any prominent links or does not wants to be registered by the search engine may remain hidden.
1.2.1.2.1. Any site can place directions in their ROBOTS.TXT file indicating whether the site can be searched or not, and if so what pages can be searched.
1.2.2. Does
1.2.2.1. Created somethingcalled the sitemaps protocol.
1.2.2.2. Which lets a Web site list in an XML file information about how the Google robot can work with the site.
1.2.2.3. Sitemaps can be useful in allowing content that isn’t browsable to be crawled; they also can be useful as guides to finding media information that isn’t normally considered, such as AJAX, Flash, or
1.2.2.4. Silverlight media. The Sitemaps protocol has been widely adopted in the industry.
2. Web
2.1. Deep Web
2.1.1. That part of the web that is not indexed by the search engines. It conatins aboyt **50%** of the entire internet.
2.1.2. Content
2.1.2.1. **Database generated webpages.**
2.1.2.2. **Dynamic content.**
2.1.2.3. **Webpages that are behind paywall.**
2.1.2.4. **Private or limited access Web pages and sites that required special access and authorization** Ex: - Govt sites.
2.1.2.5. **Pages without any links.**
2.1.3. Most of our internet time is spent on *Deep Web* without even knowing about it. Ex:- Doing payments, using mail apps like *gmail* etc.
2.2. Dark Web
2.2.1. Its a small section of the *Deep Web* that is intentionallly hidden.
2.2.2. Specialize applications are required to access the *Dark web* like **Tor** browser.
2.2.3. It is known for anonyity & privacy.
2.2.4. Content
2.2.4.1. **Black Market:**
2.2.4.1.1. Illicit goods including drugs, weapons, stolen data & more.
2.2.4.2. **Whitsleblower Platforms:**
2.2.4.2.1. Sites for anonymous sharing of information and data.
3. **Adwords**
3.1. A trageted Ad service based on matching advertisers & their keywords to users and their search profiles.
3.2. This system turned **Google** into from a competent search engine into an industry giant.
3.2.1. Responsible for majority of google's revenue stream.
3.3. **Top Competitors**
3.3.1. *Microsoft adcentre*.
3.3.2. *Yahoo! Search Marketing.*
3.4. **Configuration:**
3.4.1. Ads can be displayed as text , banner, tailored based on **IP** or **geological location**, *frequency* and other factors.
3.4.2. Adwords can also appear on other search engines aside from *google.com*
3.4.3. Other partners belonging to the Google Display Network can also display AdSense ads.
3.4.3.1. In all these cases, the AdWords system determines which ads to match to the user searches.
3.5. **Working:**
3.5.1. Advertisers bid on keywords that are used to match a user to their product or service.
3.5.1.1. If a user searches for a term such as *“develop abdominal muscles"*, Google returns products based on those terms.
3.5.1.1.1. You might see an ad with **Chuck Norris** selling a *modern day version of a torture rack* that, if it doesn’t give you a six-pack, at least makes your wallet lighter.
3.5.1.2. Up to 12 ads per search can be returned.
3.5.2. Google gets paid for the ad whenever a user clicks it.
3.5.2.1. The system is referred to as *pay-per-click* advertising, and the success of the ad is measured by what is called the **click-through rate (CTR).**
3.5.2.2. Google calculates a quality score for ads based on the CTR, the strength of the connection between the ad and the keywords, and the advertiser’s history with Google.
3.5.2.2.1. This quality score is a Google trade secret and is used to price the minimum bid of a keyword.
3.6. In 2007, Google purchased **DoubleClick,** an Internet dvertising services company.** DoubleClick** helps clients create ads, provides hosting services, and tracks results for analysis
3.6.1. **DoubleClick** ads leave *browser cookies* on systems that collect information from users that determine the number of times a user has been exposed to a particular ad, as well as various system characteristics.
3.6.2. Some **spyware** trackers flag **DoubleClick** cookies as **spyware.** Both ** AdWords** and **DoubleClick** are sold as packages to large clients.