search engines
Download
Skip this Video
Download Presentation
Search Engines

Loading in 2 Seconds...

play fullscreen
1 / 30

Search Engines - PowerPoint PPT Presentation


  • 96 Views
  • Uploaded on

Search Engines. Introducing. Directories, Meta-Searchengine How search engines work What influences the ranking. Directories. hand-constructed hierarchy of topics (e.g. Yahoo!) use human editors for page selection, indexing and classification Covers a small part of the web

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Search Engines' - grady-tyler


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
search engines

Search Engines

Thomas Haidlas

introducing
Introducing
  • Directories, Meta-Searchengine
  • How search engines work
  • What influences the ranking

Thomas Haidlas

directories
Directories
  • hand-constructed hierarchy of topics (e.g. Yahoo!)
  • use human editors for page selection, indexing and classification
  • Covers a small part of the web
  • Small updatability
  • No ranking

Thomas Haidlas

directories ii
Directories II
  • No searching across the index
  • Searching across the reviews
  • Sometimes partnership with search engines to increase coverage

Thomas Haidlas

meta searchengine
Meta-Searchengine
  • Rare keyword requests require use of more than one web search engine
  • Submit the same query parallel to many engines
  • Duplicated entries are eliminated
  • The results are shown in uniform format
  • No harvesting or indexing

Thomas Haidlas

how search engines work
How search engines work
  • Harvesting
  • Indexing
  • Analyzing Requests
  • Ranking

Thomas Haidlas

harvesting
Harvesting
  • programs (robots, gatherer or crawler )visit web sites and gather the web pages for indexing
  • Start with an initial page
  • Follows hyperlinks (<a href=…>)
  • Sometimes, more then 2 sub-levels are visited
  • These programs are started periodically

Thomas Haidlas

harvesting ii
Harvesting II
  • Problems:
    • Links aren‘t found in
      • Frames
      • Imagemaps
    • Many robots are started by a search engine

=> traffic

Thomas Haidlas

robot exclusion
Robot Exclusion
  • Two Methods:
    • Meta-Tags:

<meta name="robots" content=„noindex,nofollow">

    • robots.txt:

User-agent: Scooter

Disallow: /privat/geht_dich_gar_nix_an.html

Allow: /allesOffen

Thomas Haidlas

robot exclusion ii
Robot Exclusion II
  • robots.txt (Example 2):

User-agent: *

Allow: /allesOffen

Thomas Haidlas

indexing
Indexing
  • Indextable gets the harvesting-resuls
  • Indextable includes keywords
  • Table is located in main-mamory => fast access

Thomas Haidlas

analysing requests
Analysing Requests
  • Comparison between searchstring and index-table
  • The searchstring consists of a word:

=> easy processing

  • The search word consists of truncation or booleans:

=> complex processing

  • If the searchstring in the index is discovered, the side is taken up to the hit-list

Thomas Haidlas

ranking
Ranking
  • influences on the ranking:
    • How many keywords are found
    • keyword-frequency
    • keywords-position:
      • Domain/URL
      • Documentname

Thomas Haidlas

ranking ii
Ranking II
      • Headline
      • Early in the text
      • Meta-Tags
  • Ranking for cash
  • Page Rank
  • Clicking frequency/ Hit Popularity Engine

Thomas Haidlas

ranking for cash
Ranking for cash
  • Capitalism principle
  • Paying money => high ranking-level
  • Contents are not relevant
  • additional incomes

Thomas Haidlas

ranking for cash ii
Ranking for cash II
  • not independently in the employment
  • Mostly used by e-commerce-companies
  • Second method:
    • pay for faster indexing time

Thomas Haidlas

page rank google
Page Rank (Google)
  • Evaluation through internet-community (web-admins)
  • Realtion between quality of a page and number of links that point to it
  • Links of the popular web-sites are regarded as better

Thomas Haidlas

page rank google ii
Page Rank (Google) II
  • Disadvantage:
    • new web-sites have a bad ranking
    • Querys with many boolean-connections and keywords are not easy to process

Thomas Haidlas

hit popularity engine
Hit Popularity Engine
  • index already exists and is pre-sorted
  • A click on a link leads to a voting for this site concerned => „click“ is recorded to the database
  • pages with many „clicks“ are more popular
  • developed by „Direct Hit“

Thomas Haidlas

hit popularity engine ii
Hit Popularity Engine II
  • This method is usually combined with others
  • Disadvantage:
    • new web-sites have a bad ranking

Thomas Haidlas

ranking m anipulation
Ranking-Manipulation
  • Why?
    • commercial interest
  • Done of:
    • Search Engine Optimizer, SEO
  • Sense of:
    • to boost the pagerank

Thomas Haidlas

linkfarm
Linkfarm
  • Many Domains are registered
  • Programs generate thousands among themselves linked pages
  • each page contains keywords
  • Partly these sides are arranged even complex

Thomas Haidlas

forwarding
Forwarding
  • intermediate page contains the looked for terms
  • HTML Meta tags and simple Javascript can be recognized
  • SEO‘s complicate the forwarding instructions => no recognizing

Thomas Haidlas

ip delivery
IP Delivery
  • normal site is indicated by Robots
  • After this, contents of the site are exchanged

Thomas Haidlas

ip cloaking
IP Cloaking
  • Servers programs determine who the Request starts
  • Robots request: "cloaked" content is delivered which is designed to influence ranking
  • Human visitors: do not see the "cloaked" content

Thomas Haidlas

other simple tricks
Other simple tricks
  • Links in guestbooks
    • particularly effectively with high-ranking guestbooks
  • „Blind Text“
    • Text in background-color

Thomas Haidlas

trade with weblinks
Trade with weblinks
  • Paying for linking
  • Partnership =>Commission

Thomas Haidlas

resumee
Resumee
  • suitable tools select
  • The www is dynamic =>

new developments consider

  • correct estimate of ranking

Thomas Haidlas

thank you
Thank You!

Thomas Haidlas

sources
Sources
  • [1] www.suchfibel.de
  • [2] Jo Bager Orientierungslose Infosammler c‘t 23/99
  • [3] Stefan Karzauninkat Zielfahndung c‘t 23/99
  • [4] Sven Lennartz Ich bin wichtig c‘t 23/99
  • [5] Stefan Karzauninkat Google zugemüllt c‘t 1/03
  • [6] www.google.com/webmasters
  • [7] Dr. Wolfgang Sander-Beuermann Schatzsucher c‘t 13/98
  • [8] Arno Dittmar Suchmaschinen und Anfragen im WWW
  • [9] Ralf RudolfSuchmaschinen und Anfragen im WWW

Thomas Haidlas

ad