How Search Engines Work?
Search engines are called 'robots' or 'spiders' as
they works by sending out spiders. A Spider is a computer program
that search and fetch information across Internet. After completion
of the task of fetching information by the spiders, the search
engine stores the information in a useful and accessible format
often called as a database.
Indexer
Then another program, called indexer, reads these gathered
information and creates an index, based on the words that are
present in those gathered information. The best and the most
effective way to create an index is by building hash table. In
hashing, a formula is applied on each word to provide a numerical
value to the word.
Search engine uses algorithm
An unique formula to fetched web sites thus returning meaningful
results for each query. The algorithms take the on-page and off-page
elements into consideration to provide ranking to the pages in their
search results.
These algorithms frequently undergo refinements
and improvements to give better and relevant results. Many search
engines form partnerships and buy technologies to improve their
algorithms.
Database
When a new or an updated site is found, they copy some information
about the site back to their home database. It is this database
which provides information when something is searched. All the above
defined elements are taken into consideration to offer positioning
and ranking.
Even several search engines rely on similar
factors in determining the website's ranking but still rank the same
site differently.
Search engines form partnerships to provide
their visitors with better hybrid services
Sites combining search engines and directories. All major search
engines provide hybrid services. Some search engines compile their
own directories and databases while others buy services from other
engines.
Most of the search engines use different
technologies to achieve better and relevant results to enhance and
improve their technologies.
Some search engines also charge for their service.
This type of service is referred as paid listings which depend on a
cost-per-click or CPC. They are also referred as PPC or pay per
click search engines. Advertisers of the websites pay for every
click the search engine sends to them. The website advertisers who
pay the most are generally listed at the top position in a search
engine.
Search engine features
Generally the Search Engines are specialized in
one or more of the following features:
Most of the search engines display too many
matches in a casual or general search, so their provided search
tools play the role of the most significant factor. Search engines
usually have a nice GUI interface which allows to type words into
their form (search box).
They also allow Boolean searches; i.e. the user
can use Boolean keywords (AND, OR, NOT, ANDNOT etc) & Boolean
operators ('+' & '-') to specify combinations of words. Open Text
are also permitted to specify a search. The search form of search
engines provides many menus, making a complex Boolean search fast
and easy. It also permits to specify that one wants to search only
titles or URLs.
One can restrict a search to phrases in anchors,
pages from a specific host, image titles, links, text, document
titles, or URLs using this feature with the syntax -- keyword:
search-word.
The databases vary in size from engine to engine.
Some provide large database while some have a very small database.
Even few search engines do not have a database at all. Such search
engines borrow results from databases of other search engines or a
combination of different databases provided by different search
engines.
Catalog refers to group of listings arranged
categorically. Search engines provide different categories to make a
search easier and more specific.
There are various search features that can be
commonly defined for all search engines. The available search
features are Boolean Search, Proximity, Truncation & Stemming, Case
Sensitivity, Field Search, Limits, File Types, Stop words, Sorting
etc. But the entire above mentioned search features are not
supported by all search engines
Search engine toolbars
As most of the Search engines are GUI based they
offer toolbars to make the search engines more attractive and user
friendly. There are few toolbars which are common to many search
engines. Few search engines also provides their special toolbars
with many special features.
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