  It is worth noting that advertising schemes used by search engines have evolved over time. For example, Diaz (2008, 21) points out that banner ads, which were common on the Internet during the Web 1.0 era, have been replaced by “paid placement of ads.” He also notes that “paid listings” (unlike the earlier banner ads) do not always look very different from the normal results returned to users. Elgesem (2008) points out that search engines such as GoTo, whose lists of search results were based entirely on “paid hits” from advertisers, allegedly failed because of user dissatisfaction with the results they received. Eventually, however, GoTo was taken over by Google, which continued to use GoTo’s method for generating paid-ad-based search results but physically separated those results from the “organic” results that appear on the center of its pages (Elgesem 2008); this scheme, which contrasts the two different kinds of results, seems to have been accepted by Google users.