a software facility for creating an incentive to author useful item reviews (“ the facility ”) is described . in some embodiments , the facility is used by a web merchant to obtain content that , when incorporated in the web merchant &# 39 ; s web site , helps to draw interest to the web site and to increase the number of customers that may buy items from the web merchant . the facility provides such an incentive by rewarding the authors of reviews found to be useful by their readers , such as by prominently displaying their names and ranks as authors of useful reviews prominently on the web merchant &# 39 ; s web site . in some cases , review authors ( also called “ reviewers ”) submit reviews each relating to a specific item sold by the web merchant . the web merchant displays these reviews to customers in conjunction with the items to which they relate , together with a control — such as buttons — that may be used by viewing customers to vote on how useful the review is to them . for example , in some embodiments , the control enables viewing customers to specify either that they found the review useful or that they did not find the review useful . the facility stores these votes , and periodically uses them to score each reviewer in terms of the number of reviews that the reviewer submitted and their level of usefulness . each time new scores are generated , the facility ranks the reviewers in descending order of their scores . these rank values are then typically displayed liberally in conjunction with information about the top - ranked reviewers . for example , the facility may display a list of the top - ranked reviewers , in which the rank of each reviewer is indicated . the facility may also display a shorter list of reviewers randomly selected from among the top - ranked reviewers , such as from the top 100 reviewers . such displays may include such information as the names of these reviewers , their pictures , and biographical sketches . the facility may display in conjunction with any occurrence of a top - ranked reviewer &# 39 ; s name an indication of that reviewer &# 39 ; s rank . for example , occurrences of the name of the reviewer having rank 1 may be accompanied by a “# 1 reviewer ” message , which the name of the reviewer having rank 89 may be accompanied by a “ top 100 reviewer ” message . such displays may occur on pages such as a home page for the reviewer , or in conjunction with the reviewer &# 39 ; s reviews . by promoting reviewers that submit reviews that prove to be useful to their readers , the facility motivates many of the users visiting the web merchant &# 39 ; s web site to prepare and submit useful item reviews . this in turn typically increases the level of traffic to the web merchant &# 39 ; s web site ( in terms of number of visitors , average frequency with which a single user visits , and average duration of a visit ), the number of sales completed and therefore the profitability of the web merchant , and the level of satisfaction of item purchasers , both with respect to their purchases specifically and with respect to the web merchant generally . fig1 is a high - level block diagram showing a typical environment in which the facility operates . the block diagram shows several client computer systems , such as client computer systems 110 , 120 , and 130 . each of the client computer systems has a web client computer program for browsing the world wide web , such as web clients 111 , 121 , and 131 . the client computer systems are connected via the internet 140 to a server computer system 150 hosting the facility . those skilled in the art will recognize that client computer systems could be connected to the server computer system by networks other than the internet , however . the server computer system 150 contains a memory 160 . the memory 160 preferably contains web merchant software 161 incorporating both the facility 162 and data typically used by facility , such as item reviews 163 , votes 164 on item reviews , and item order and / or sales data 165 . the memory preferably further contains a web server computer program 166 for delivering web pages in response to requests from web clients . while items 161 - 166 are preferably stored in memory while being used , those skilled in the art will appreciate that these items , or portions of them , maybe be transferred between memory and a persistent storage device 172 for purposes of memory management and data integrity . the server computer system further contains one or more central processing units ( cpu ) 171 for executing programs , such as programs 161 , 162 , and 166 , and a computer - readable medium drive 173 for reading information or installing programs such as the facility from computer - readable media , such as a floppy disk , a cd - rom , or a dvd . while various embodiments are described in terms in the environment described above , those skilled in the art will appreciate that the facility may be implemented in a variety of other environments including a single , monolithic computer system , as well as various other combinations of computer systems or similar devices connected in various ways . fig2 - 5 show examples of ways in which the facility promotes , and thereby rewards , top - ranked reviewers . fig2 is a display diagram showing a typical display presented by the facility showing a list of top - ranked reviewers . the display 200 is displayed as part of the web site of web merchant amazon . com . the display includes to laudatory language 201 congratulating the top - ranked reviewers . the display also includes an ordered list 210 of the top - ranked reviewers . list 210 is comprised of ordered entries , each corresponding to one top - ranked reviewer , such as entries 220 , 230 , and 240 . as an example , entry 220 contains information about the highest - ranked reviewer , harriet klausner . this entry contains the reviewer &# 39 ; s rank 221 , as well as a graphical characterization 222 of the rank . the entry further contains the name of the reviewer 223 , which is a link that the user can select in order to view more detailed information about this reviewer . the entry further contains an indication 224 of the total number of reviews authored by this reviewer . the entry also contains further information 225 about the reviewer , typically provided by the reviewer him or herself . this information includes a link 226 that may be selected by the user to display additional information about the reviewer . some entries contain an image of the reviewer , such as image 237 shown in entry 230 . in addition to the list 210 of detailed entries about the top - ranked reviewers , the display also contains a more abbreviated list 250 of the top - ranked reviewers . in this list , each entry is merely the rank value and the name of the reviewer , which is a link that may be selected by the user to display additional information about the reviewer . fig3 is a display diagram showing a typical display presented by the facility containing more detailed information about a particular top - ranked reviewer . in particular , the display 300 shown in fig3 is displayed by the facility when the user selects link 243 for the reviewer frank behrens shown in fig2 . the display includes a profile 310 for the reviewer , which include such information as the reviewer &# 39 ; s name 311 , a nickname 312 for the reviewer , an email address 313 for the reviewer , the current rank 314 of the reviewer , the beginning of a biographical sketch 315 of the reviewer , a link 316 to the entire biographical sketch of the reviewer , a count 317 of the number of reviews submitted by this reviewer , a count 318 of the number of positive votes cast for the reviews of this reviewer , and a graphical indication 319 of the rank of the reviewer . the display further contains each of the reviews submitted by the reviewer . as an example , the display contains information 320 about the reviewer &# 39 ; s most recent review . this information includes information 321 about the reviewed item , such as the title , artist , format , price , and availability of the item , as well as a link 322 that may be used to display more information about the item , and a control 323 that may be used to place an order for the item . the information 320 also includes a grade 324 assigned by the reviewer to the item as part of the review — here the grade shown is four stars out of five stars ; the review &# 39 ; s title 325 ; the date 326 on which the review was submitted ; and the text 327 of the review . the display also contains a section 330 containing links to item categories for which the reviewer has submitted reviews . fig4 is a display diagram showing a typical display presented by the facility containing detailed information about an item . in this case , the item is the tchaikosvky symphony no . 6 dvd whose review is shown in fig3 . the display 400 shown in fig4 is displayed in response to the selection of link 322 shown in fig3 . in addition to other information about the item , the display includes a list of reviews submitted for the item . these include review 413 submitted by the reviewer frank behrens . the review 410 includes the reviewer &# 39 ; s name 411 , which is a link to the display shown in fig3 ; a graphical indication 412 for the current rank of the reviewer ; the item grade 413 assigned to the item as part of the review ; the review title 414 ; the text of the review ; and voting buttons 415 and 416 . a user that is undecided about buying this item may read review 410 . based upon various aspects of the review , the user may either find the review helpful in deciding whether to purchase the item or unhelpful in deciding whether to purchase the item . such a user may select button 415 if the review was helpful , or button 416 if the review was not helpful . in some embodiments , such votes are the basis on which the facility scores and ranks this reviewer . the display further includes a link 421 that the user may select to submit his or her own review of the tchaikosvky symphony no . 6 dvd item . fig5 is a display diagram showing a typical display presented by the facility incorporating information about two randomly - selected top - ranked reviewers . the display 500 includes a list 510 of randomly - selected top - ranking reviewers . the list is comprised of one or more entries , such as entries 520 and 530 shown here , which each relate to one randomly - selected top - ranked reviewer . for example , entry 520 relates to reviewer number 14 , and includes the reviewer &# 39 ; s rank value 521 ; the reviewer &# 39 ; s name 522 , which is a link which that the user may select in order to display more information about this reviewer ; the number of reviews submitted by this reviewer 523 ; and the number of positive votes 524 received by this reviewer &# 39 ; s reviews . some entries contain an image of the corresponding reviewer , such as image 535 in entry 530 . the display also includes a link 540 to the top reviewer &# 39 ; s list shown in fig2 . fig6 - 8 show an example of an approach to obtaining an item review submitted by a reviewer . fig6 is a display diagram showing a typical display presented by the facility to enable a user to submit a new review . the user typically selects this display in conjunction with a particular item , for which the user can submit a review . for example , display 600 is displayed in response to the user &# 39 ; s selection of link 421 in the display containing detailed information about the tchaikovsky symphony no . 6 dvd shown in fig4 . the display includes the identity of the user , which is attributed as the identity of the reviewer . to attribute a different identity to the reviewer , the user can select link 602 . the display includes information 603 identifying the item to be reviewed . the display includes a control 604 used by the user to specify a grade or rating for the reviewed item . the display includes field 605 for entering a title for the review . the display includes field 606 for entering the text of the review . the user may select radio button 607 in order to display a reviewer name with the review , which may edited in field 608 . alternatively , the user may select radio button 609 to make the review anonymous and prevent the review from being associated with the reviewer &# 39 ; s name . the display also includes field 610 for entering the author &# 39 ; s location . before preparing the review as described , the user may select link 621 in order to display guidelines for preparing the review . the user may also select link 622 in order to display one or more example customer reviews demonstrating compliance with the review guidelines . when the user has assembled the review to be submitted using the above described aspects of the display , the user selects button 611 . fig7 is a display diagram showing a typical display presented by the facility containing guidelines for preparing an item review . the display 700 contains typical guidelines for this activity . fig8 is a display diagram showing a typical display presented by the facility containing sample reviews . the display 800 includes sample reviews , such as sample review 810 . in some embodiments , sample reviews are chosen from among the reviews of top - ranked reviewers , such as from the reviews of the top - ranked 100 reviewers . fig9 is a flow diagram showing steps typically performed by the facility in order to process a new item review submitted by a reviewer . in step 901 , the facility receives a new item review from a reviewer . such a new item review may be received in a variety of ways , including receiving it using a web - based form as shown in fig6 , receiving it via electronic mail , receiving it in a document uploaded to an ftp server , receiving it in paper form , receiving it in audio form , etc . in step 902 , the facility assigns the review identifier to the review that will be used to identify the review and stores the received review in conjunction with the assigned review identifier . in step 903 , the facility creates an association between the assigned review identifier and an identifier for the reviewer . as an example , table 1 below shows information stored in a data structure , and , in particular , rows stored in a table , in order to create such an association . for example , the first row shown in table 1 indicates that the item review having review identifier 96335807 was submitted by the reviewer having reviewer identifier 449603151134 . in step 904 , the facility obtains editorial approval for the review . as an example , the facility may in step 904 add the review or its review identifier to a queue of new reviews to be subjected to a manual editorial review process . step 904 is optional , and may be applied selectively , such as to reviews submitted by reviewers that have a reviewer score below a certain threshold , or a reviewer rank value above a certain threshold . alternatively , the new review may be added to such a queue at different points depending upon the score or rank of the submitting reviewer . in step 905 , after editorial approval has been received for the review , the facility makes the review available on the web site . this may involve , for example , incorporating the review in a display such as those shown in fig3 , 4 , and 8 . again , step 905 may be performed in a manner sensitive to the score and / or rank of the submitting reviewer . after step 905 , these steps typically conclude . fig1 is a flow diagram showing steps typically performed by the facility in order to process votes received for published item reviews . in step 1001 , the facility receives a vote on a review from a voter . for example , the facility may receive an indication that a user pressed a button like button 415 shown in fig4 indicating that a review was helpful to the user , or a button like button 416 shown in fig4 indicating that a review was not helpful to the user . such a vote typically identifies a review to which the vote relates , an identifier identifying the voter , the date and time at which the vote was cast , and the value of the vote , i . e ., whether the voter indicated that the review was helpful or not helpful . in step 1002 , the facility stores this information together . for example , this information may be stored in an entry of a data structure , such as a row of a table , as shown below in table 2 . for example , it can be seen from the first row shown in table 2 that a vote on the review having review identifier 96335807 , cast by a voter having voter identifier 919654002315 , was cast at 16 : 04 : 02 on apr . 11 , 2001 , and that this vote indicated that the review was helpful . after step 1002 , these steps typically conclude . fig1 is a flow diagram showing steps typically performed by the facility to update reviewer scores and rankings . the facility typically performs these steps periodically , such as once per day . in step 1101 , the facility identifies reviewers whose reviews have received at least one new vote . in some embodiments , step 1101 involves selecting from the stored votes those votes cast on the date immediately preceding the current date . the review identifiers in the selected votes are used to identify the reviewer identifiers corresponding to the selected votes . in steps 1102 - 1104 , the facility loops through each reviewer identified in step 1101 as having received at least one new vote . in step 1103 , the facility calculates an updated reviewer score for the current reviewer . the facility is preferably configurable to use a wide variety of different approaches to determining reviewer scores . in one approach , the facility calculates a reviewer score based upon scores calculated for each review of the reviewer . in accordance with this approach , for each review , the facility applies formula ( 1 ) below . where a is the number of reviews submitted by the author for which at least 3 positive indications were received , b is the number of reviews submitted by the author for which at least 10 positive indications were received , c is the number of reviews submitted by the author that were the first reviews submitted for the corresponding item and for which at least 3 positive indications were received , d is the number of reviews submitted by the author for which at least 3 more negative indications than positive indications were received , and e is the number of reviews submitted by the author for which at least 10 more negative indications than positive indications were received . in some embodiments , the facility excludes from values a through e any votes that ( 1 ) were subsequent to the first vote cast by the same voter on the same review , or ( 2 ) were subsequent to the fifth vote by the same voter on any review by the same reviewer . various other approaches to calculating a score for a review may also be employed by the facility , such as those in which fewer or more factors are considered , or such factors are weighted differently . additional factors that various embodiments may consider includes such factors as whether the review is the first review submitted for a particular item , and the number of orders that have been placed for an item by a customer to which the review has been displayed . the score for a reviewer is generated by summing the scores of the reviewer &# 39 ; s reviews as shown below in formula ( 2 ). in various embodiments , a reviewer &# 39 ; s score may be determined by combining the scores for the reviewer &# 39 ; s reviews in a variety of other ways . after step 1103 , the facility continues in step 1104 . in step 1104 , if additional identified reviewers remain for processing , the facility continues in step 1102 to process the next identified reviewer , else the facility continues in step 1105 . in step 1105 , the facility attributes a rank value to each reviewer based upon their reviewers scores , as updated . in step 1106 , the facility proceeds to utilize the reviewer rank values attributed in step 1105 in any web pages of the web &# 39 ; s web site that reference these rank values . this may involve , for example , utilizing the attributed reviewer rank values in a display such as those shown in fig2 - 5 . after step 1106 , these steps typically conclude . it will be understood by those skilled in the art that the above - described facility could be adapted or extended in various ways . for example , the facility may be operated by others besides web merchants . a variety of different types of rewards may be offered to reviewers submitting useful reviews . the usefulness of reviews may be discerned in a variety of different ways . while the foregoing description makes reference to preferred embodiments , the scope of the invention is defined solely by the claims that follow and the elements recited therein .