The work of the search engine is divided into three stages, i.e.
crawling, indexing and retrieval.
1)
Crawling
The search engines have the web crawler or spiders to perform crawling.
The task of crawler is to visit a web page, read it and follow the links to
other web pages of the site. Each time the crawler visits a webpage it makes a
copy of the page and adds its URL to the index. After adding the URL it
regularly visits the sites like every month or two to look for updates or
changes.
2)
Indexing
In this stage, the crawler creates the index of the search engine.
The index is like a huge book which contains a copy of each web page found by
the crawler. If any web page changes the crawler updates the book with new
content.
So, the index comprises URL of different web pages visited by the
crawler and contains the information collected by the crawler.
3)
Retrieval
This is the final stage in which the search
engine provides the most useful and relevant answers in a particular order.
Search engines use algorithms to improve the search results so that only
genuine information could reach to the users, e.g. Page Rank is a popular
algorithm used by search engines. It shifts through the pages recorded in the
index and shows those web pages on the first page of results that it thinks are
the best.
Google Algorithm Updates
In the beginning, in 90's, search engines was not as effective as
it is today; it was mainly focused on keyword matching and back links. So, it
was quite easy for the low-quality websites to rank higher by targeting their
exact keywords with lots of back links.
To solve this problem, Google introduced a algorithm to filter the
results so that it could clean the web. Since then Google is continuously
updating its algorithm to maintain and improve the efficiency of its search
engine.
Some of the major
Google updates which helped it filter sites more precisely
and clean the web effectively are given below:
2016
Updates
Penguin
4.0
Penguin 4.0 was announced on September 23, 2016, with few changes
like it will be part of core algorithm, will update in real time and will be
page specific instead of affecting the entire domain.
Mobile
Friendly Boost Update
It was launched in May 12, 2016, to help mobile-friendly sites on
mobile search.
2015
Updates
Panda
4.2
On 17 July 2015, Google rolled out Panda refresh (Panda 4.2). It
has no immediate effect on rankings. According to Google, it impacted 2?3 % of
English language search queries.
Mobile-Friendly
Update (Mobilegeddon)
It was rolled out on 21 April, 2015. It made mobile-friendliness
an important ranking factor for mobile searches. Its job was to boost the
rankings of mobile-ready pages so that quality and relevant content could be
provided to mobile users.
2014
Updates
Penguin
3.0
It was introduced on 17 October 2014. It was just a refresh that
helped those websites boost their ranking who were de-ranked in the previous
update (Penguin 2.1).
Panda
4.1
It was the 27th version of Panda released by
Google on 23 September 2014. Google said that it will help search engine
identify poor content so that small or medium sized websites with quality
content could rank better.
Pigeon
It was rolled out in July 2014, for local businesses. Google said
that it will create closer ties between local and core algorithms so that
people could find useful and accurate information in local search results.
Panda
4.0
This Panda update was introduced on 19 May 2014, to help small
websites and businesses with limited resources. It was a change a data refresh;
a change in Panda algorithm.
2013
Updates
Hummingbird
1.0
It was introduced by Google on 20 August 2013 to better understand
the changing face of the Web. It was capable of understanding the intent of
long search terms instead of just recognizing specific keyword. It helped
Google recognize long-tail search terms and accurately rank answers to such
long-tail keywords. It enabled users to ask questions and get appropriate
answers.
2012
Updates
Penguin
It was introduced on 24th April 2012 to target the
sites that were spamming the search results by buying links or using some other
link networks designed specifically to boost rankings. Google issued warnings
through Webmaster tools and penalized the sites for not following its
guidelines.
2011
Updates
Panda/Farmer
It was first launched on Feb24 2011. This algorithm was used to
assign a score to webpages based on the quality of the content and de-rank the
sites with low-quality content. Its job was to identify and de-rank content
farms, sites offering thin content or sites with high ad-to-content ratio.
2010
Updates
Caffeine
In June 2010, Google updated its caffeine algorithm to introduce
new web indexing system. It helped Google to improve the speed of search engine
and integrated crawling and indexing that resulted in a fifty percent fresher
index.
2009
Updates
Caffeine
(Preview)
In August 2009, Google released Caffeine (Preview); the upcoming
infrastructure change to improve and integrate indexing, crawling and range of
their search engine index.
Vince
It was introduced in February 2009. It was seen as a big change
that would favor big brands but Google?s Matt Cutts cleared that it was a minor
change focused on ranking signals like trust and authority.
2007
Updates
Buffy
It was introduced in June 2007. This update was named in honor of
Google's Vanessa Fox. Matt Cutts said that it was just some minor changes like
the integration of search results with news, images and videos, etc.
2005
Updates
Bigdaddy
It was rolled out in December 2005. It was an infrastructure
change that brought new technicalities related to URL canonicalization,
redirects, etc. It helped Google to prepare for future developments.
2004
Updates
Brandy
This update was launched in February 2004. It expanded Google?s
index and incorporated Latent Semantic Indexing (LSI) which enabled Google to
better understand synonyms.
Austin
It was introduced on 23rd January 2004. This
update was actually some improvements in the Florida update. It targeted the
on-page spam tactics like invisible text and meta-tag stuffing.
2003
Updates
Florida
It was introduced on 16 November, 2003. It brought significant change
to Google's algorithm and put an end to the use of keyword stuffing to
manipulate search engine results.
Fritz
It was introduced in July 2013. With this update Google changed
its way of updating the index; now instead of indexing on a monthly basis, it
started indexing on daily basis.
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