《信息科學(xué)類專業(yè)英語》課件第15章

Lesson15HowDoSearchEnginesWork?

(第十五課搜索引擎如何工作？)

Vocabulary(詞匯)ImportantSentences(重點(diǎn)句)Multiple-choiceQuestion(多選題)

Problems(問題)

Oneofthebiggestreasonswhymanyorganizationsarenotdoingevensimplethingstohelppeoplefindtheirwebsitesinsearchenginesistheysimplydon’tunderstandhowsearchengineswork.Thisarticleisintendedtoexplainthebasicsofhowsearchenginesworkandinthecourseofdoingsoshattersomesearchenginemythsandhelpyouunderstandwhatyoucandotohelppeoplefindyourwebsiteinsearchengines.1WhatisaSearchEngine?

Thefirsttosteptounderstandinghowsearchenginesworkistounderstandwhatasearchengineis.Thesimplestexplanationisthatsearchengineisatoolforfindingthingsonline.Therearemanydifferenttypesofsearchenginesbuttheycanbeputintotwomajorcategories.

1.1Human-PoweredDirectories

Thefirst“searchengines”werenotactuallysearchenginesaswethinkofthemtoday,butsearchabledirectoriesofwebsitesorganizedbyhierarchicalcategories.Asiteisaddedtoadirectorywhenthewebsiteownerfillsoutasubmissionformonthedirectory’swebsiterequestingtheirsitebeincludedinthedirectoryandincludetheirwebsite’stitle,description,URL(webaddress),andcategory.Amoderatorlaterreviewsthesiteandifitmeetsthedirectory’scriteriaalistingforthatsiteisaddedoractivated.TheoriginalYahoowasoriginallyahuman-powereddirectory,anddirectorieslikeOpenDirectoryProjectcontinueontoday.

Thedownsideofthehuman-poweredsearchengineisthatitonlyincludeswebsitesthathavebeensubmittedtoit,whichmeansyoumaynotfindwhatyou’relookingforespeciallyifit’sanewwebpage.[1]Theotherdownsidefromthedirectories’pointofviewisthatreviewingeverysitesubmittedisverylabor-intensiveandcostly.Iknowbecausemycompany’s“searchengine”,OurChurch.Com’sDirectoryofChristianWebsites,likealmostallchurch/Christian“searchengines”,isahuman-powereddirectory.

1.2Crawler/Spider-PoweredSearchEngines

Thenextgenerationofsearchengineshasprogramswhichactivelyseekoutnewsitesandreadthemintotheirindexes.Theseprogramsarecalledcrawlers,spiders,robots,orbots.Alloflargestandmostpopularsearchenginestodayareofthistype,includingGoogle,Yahoo,MSN,andAsk.Therestofthisarticleisfocusedonhowthesecrawler/spider-poweredsearchenginesworkbecausemorethan99%ofsearchesaredoneonthistypeofsearchengine.2TheCrawler

(1)?Searchbotsperiodicallyrereadeverywebpageintheirdatabase.Whydoesthismatter?

Youdon’thavetodoanythingwhenyouchangeyoursite.Ifyoursiteisalreadylistedinasearchengineandyoumakechangestoyourwebsite,searchengineswilleventuallyupdatetheirinformation.

Youdohavetobepatient.Thefrequencyofre-crawlingvariesdependingonthesearchengine,theimportanceofyoursite(asdeterminedbythesearchengines),andhowoftenyouupdateit.Itcouldtakeadayoritcouldtakemorethanaweek.

(2)?Searchbotsfollowlinksonthepagesthathavealreadybeencrawledinordertofindnewpages.Whydoesthismatter?

Ifyouaddanewpagetoyourwebsiteorcreateanewwebsite,it’simportanttoaddalinktoitonawebpagethatisalreadyinthesearchengines.

Ifawebpagethatisalreadyinthesearchengineshasalinktoyournewpageornewwebsite,youdonotneedtosubmitarequesttothesearchenginestocrawlthenewpageorwebsite,thoughitmaystillbeworthdoingjusttobesureyourwebsitewillbefoundquickly.

(3)?Somesearchengineshaveformsyoucansubmittorequestawebsitebecrawled.Whydoesthismatter?

Ifyouhaveanewwebsiteandnositeslinktoit,searchbotswillnotbeabletofindit.Inthiscase,submittingaformtothesearchenginerequestingyoursitebelistedorindexedcangetitintosearchengines.

Becausehuman-powereddirectoriesdonothavesearchbots/crawlers,tobelistedinthemyoumustsubmitarequestform.[2]

2.1TheRankingAlgorithm

Sometimeafterawebpagehasbeencrawledbythesearchbotorcrawler,thesearchenginethenprocessesorindexesthepagetodeterminewhatsearchwordsandphrasesthepageisrelevanttoaswellashowrelevantthatpageiscomparedwithotherwebpagesforthosephrases.Duringthisprocessingthesearchenginelooksatmanydifferentfactorsincludinghowmanytimeseachwordandphraseoccursonthepage,whichwordsareinheadingsorbold,thedomainnameofthesite,filenameofthepage,thepagesthatlinktothepage,andmanymore.

Exactlywhichfactorsasearchenginelooksatandhowthey’reweightediscalledthesearchengine’ssearchrankingalgorithm.[3]It’slikethesearchengine’s“secretsauce.”Eachsearchengine’salgorithmisdifferentandeachisaheavilyguardedsecret.

Whydoesthismatter?

Thereistimebetweenwhenyoursiteiscrawled(orrecrawled)andwhenitisprocessedorindexed.So,itcantakeaslittleasafewhourstomanydaysorweeksbeforechangestoyourwebsitemayproducechangesinitssearchrankings.

Becauseeachsearchengine’srankingalgorithmisdifferent,awebpagecanbe#1inGooglebut#20inYahooforaparticularphrase.

Becauseeachsearchalgorithmisaheavilyguardedsecretnobodyoutsideofafewselectengineersateachsearchengineknowsexactlyhowmucheachparticularfactorweighsintotherankingsofeachsearchengine.But,peoplewhospendtheirprofessionalliveshelpingsitesrankbetterinsearchengineshavegainedverygoodideaastowhatfactorsmattermost.

Becausethesearchrankingalgorithmslookattext,headings,andotherelementsonawebpage,changingthingsonthewebpagecanchangewherethatwebpageappearsinthesearchresults.

Searchrankingalgorithmslookatfactorsoutsideofawebpage,suchastheageofawebsiteandlinkstothewebpage.So,thereareotherfactorswhichyoumayhavelessinfluenceover.

Thegoalofeverysearchengineistodisplaytotheusertheinformationorwebsitestheuserislookingfor.Inotherwordseverysearchenginewantstoprovidethebest,mostrelevantresults.Asaresult,searchenginesareconstantlyimprovingtheiralgorithmsandincludingnewfactorswhichtheythinkwillproducebettersearchresults.[4]Whydoesthismatter?Assearchalgorithmschange,sowillyourwebsite’ssearchenginerankings.

2.2TheSearchEngineResultsPages(SERPs)

Thecrawlingofwebsitesandindexingofwebpagesareconstantlygoingonevenwhennooneissearching.Thelastpartinthesearchprocessispartthatyou’reprobablymostfamiliarwith–theactualsearch.Youtypeinaword,shortphrase,orquestion,andthesearchenginedisplaysalistofwebsites.ThatlistofwebsitesiscalledthesearchengineresultspageandsometimesreferredtoastheSERPs.IfyoudoasearchandlookattheSERP,you’llnoticetwocolumns.Abovetherightcolumnitsays“SponsoredLinks”.Thesearepaidadvertisements.ThecompaniesandorganizationslistedherepayafeetoGoogleforeachpersonwhoclickstheirad,sothey’reoftenreferredtoasPay-Per-ClickorPPCads.Intheleftcolumnaretheunpaidsearchresultsalsosometimescalledtheorganicresultsornaturalresults.Thesearethewebsitesthesearchenginebelievesaremostrelevanttothesearchphrasethatwasqueried.Sometimessearchenginesalsodisplaysponsoredlinksintheleftcolumnabovethenaturalresultsorwillevenplaceablockofpay-per-clickadsinthemiddleofthenaturalresults.Sponsoredlinksarealwayslabeled,thoughnotalwaysveryclearly.3WhydoesthisMatter?

Fromthesearcher’sperspective,thereisnothingwrongwithclickingonapaidlink.Youmayfindwhatyou’relookingforthere.Butit’simportanttobeawareofwhichwebsitespaidtobeintheresultsandwhicharetherenaturally.

Fromthewebadministrator’sperspective,it’simportanttounderstandtherearetwoopportunitiestogettothetopofthesearchenginerankings,throughnaturalresultsandbypurchasingpay-per-clickadvertising.4HelptheSearchEngines

Withabetterunderstandinghowsearchengineswork,youcanmakebetterdecisionsaboutthemarketingofyourwebsitethoughsearchengines.Searchenginesneedyourhelptofindyourwebsiteandtoknowwhatwordsandphrasesit’srelevantfor.Givethemthehelptheyneed.That’swheresearchengineoptimizationcomesin,butI’llgettothatonanotherday.1.?enginen.發(fā)動(dòng)機(jī),引擎。

2.?hierarchicaladj.分等級(jí)的。

3.?downsideadj.下降趨勢(shì)的。

4.?algorithmn.運(yùn)算法則。

5.?botn.robot的縮寫。Vocabulary

[1]Thedownsideofthehuman-poweredsearchengineisthatitonlyincludeswebsitesthathavebeensubmittedtoit,whichmeansyoumaynotfindwhatyou’relookingforespeciallyifit’sanewwebpage.

人力搜索引擎的崩潰在于它只包含已經(jīng)被提交的網(wǎng)站，這意味著你不可能查詢到你想要的東西，尤其是在搜索新網(wǎng)頁(yè)的情況下。句中的第一個(gè)that引導(dǎo)表語從句，第二個(gè)that引導(dǎo)的從句作為定語從句修飾websites。關(guān)系代詞which在從句中作主語。ImportantSentences

[2]Becausehuman-powereddirectoriesdonothavesearchbots/crawlers,tobelistedinthemyoumustsubmitarequestform.

因?yàn)槿肆ξ募A沒有被列出的搜索機(jī)器人(爬行者)，因此你必須提交一個(gè)請(qǐng)求表格。句中because引導(dǎo)原因狀語從句，tobelistedinthem作為定語修飾bots/crawlers。

[3]Exactlywhichfactorsasearchenginelooksatandhowthey’reweightediscalledthesearchengine’ssearchrankingalgorithm.

實(shí)際上搜索引擎關(guān)注哪些因素以及這些因素的比重被稱為搜索引擎的搜索等級(jí)算法。句中which和how引導(dǎo)的從句是兩個(gè)并列的主語從句。

[4]Asaresult,searchenginesareconstantlyimprovingtheiralgorithmsandincludingnewfactorswhichtheythinkwillproducebettersearchresults.

結(jié)果，搜索引擎一直在改善它們的算法并且包含它們所能想到的新的因素，這一切將產(chǎn)生更好的搜索結(jié)果。句中whichtheythink作為定語從句修飾factors，整個(gè)句子的主語由一個(gè)主語從句來表示。

(1)?Accordingtothearticle,whataremajorcategoriesofsearchengi