????詢問任何一位非廣告從業者“留下印象”是何意，你很可能會得到諸如“做某件讓人記住的事情”這類合理的答復。然而，在廣告業內，“印象”的定義幾乎沒有這么簡單。為什么呢？原因在于，如果你在電視、電臺或印刷媒體上打廣告，根本沒辦法確切掌握這些廣告究竟給多少人留下了“印象”。多少人抬頭看過某個特定的廣告牌？多少人在商業廣告播出期間關注電視？所以，媒體公司歷來測量、銷售的其實是留下印象的潛力。這套體系產生了預期效果，因為營銷商可以估算多少人或許真正看到了他們的廣告，幾十年下來也計算出了這些“潛在印象”的真正價值。廣告圈所稱的CPM，即獲得每千個（潛在）印象的成本，就源自這段歷史。CPM市場不僅效率驚人，而且非常龐大，市值達數萬億美元之巨。它推動塑造了無數大品牌，并為人們喜聞樂見的新聞和娛樂內容的創造提供了資金。

????接著，數字時代來了。

????借助于數字媒體，媒體公司和廣告客戶終于可以知道到底有多少人看到了它們的廣告。科技讓市場來衡量實際的印象，而不是潛在的印象。但有一個問題：盡管比起傳統的“潛在印象”，“實際印象”要更加罕見，更有價值，但數量更龐大的“潛在印象”業已成了數十億美元的市場形成的基礎。

????為了滿足需求，同時讓這項定義與電視和其他不易衡量的版式保持一致，廣告客戶和媒體出版商都同意有意維持“印象”的松散定義。這個故意留下的漏洞旨在維系“印象”市場的流動性。問題是，在數字時代，媒體公司可以簡單地創造印象。起初，它們具備低價值，但就如同任何一件擁有無限供給的事物一樣，這個行業最終創造了零價值“印象”。為了方便理解這兩個例子，設想你擁有一個網頁。今天你在這個網頁上發布了兩則廣告，然后你重新設計，到了明天，你就發布了10則廣告。你剛剛“創造了”更多的印象，但并沒有贏得更多的關注（而這恰恰是廣告客戶尋求的東西），自然也就沒有帶來更多的消費支出（這是廣告客戶的終極目的）。這只不過是價值更低的印象。更大的問題是，鑒于印象的寬泛定義，那些真正精通互聯網的人士完全可以創造沒有人能看到的“印象”，比如在網站背景上播放視頻或者制造虛假流量【在《廣告周刊》(AdWeek)的一篇文章中，邁克?希爾茲列舉了一個采用這種手法的絕佳例證】。

????所有這些低質量和欺騙性的印象持續壓低高質量內容生產商因“真正的”印象而獲得的價格。好吧，你或許會說，那又怎樣？如果存在這么多欺詐行為，價值就應該下降。說的沒錯，但隨著印象價格的下降，高品質內容公司面臨三種選擇：

????1. 把越來越多的廣告加載到內容之中（這種做法對消費者不利，他們反過來會尋找一種避免觀看這些廣告的方式，從而持續降低印象的價值）。

????2. 找到一種讓消費者為無廣告內容付費的方式【家庭影院頻道(HBO)，PandoraOne廣播頻道、奈飛公司(Netflix)和資訊網(The Information)就是這樣做的】。

????3. 關門大吉。

????Ask someone who doesn't work in advertising what it means to "make an impression," you will likely get a reasonable response like "to do something that someone remembers." However, inside the advertising industry, the definition of "impression" is not nearly as simple. Why? Because if you run an advertisement on TV, radio, or print, you have never been able to tell exactly how many people those advertisements really made an "impression" on. How many people looked up at a particular billboard? How many people paid attention to the TV during the commercial? So what media companies have historically measured -- and sold -- is really the potential to make an impression. This system worked because marketers could make estimations on how many people might actually see their advertisements and over decades figured out the real value of these "potential impressions."From this history came the cost per thousand (potential) impressions, better known as CPM in media industry. The CPM market was astonishingly effective, and large, to the tune of trillions of dollars. It drove the creation of major brands and subsidized the creation of the news and entertainment content people love.

????And then digital came along.

????With digital media, media companies and advertisers could finally know exactly how many people saw their advertisements. Technology allowed the market to measure actual impressions, rather than potential impressions. But there was a problem: While "actual impressions" were much more rare, and much more valuable than the traditional "potential impressions," the multibillion dollar market had already been created on the more numerous "potential impressions."

????In order to meet the demand and to keep the definition in line with TV and other less measurable formats, advertisers and media publishers alike agreed to keep the definition of an impression intentionally loose. This was a loophole created to help keep the market for "impressions" liquid. The problem was that in digital, media companies could simply create impressions. At first they were low value, but as with anything that has an infinite supply, the industry was eventually creating "impressions" that had zero value. For examples of both, imagine that you have a web page, today you have two ads on that web page, and then you redesign so that tomorrow you have 10. You just "created" more impressions. But there isn't any more human attention (what advertisers are seeking) and there is no more human spending (what advertisers are really seeking). And that is just lower value impressions. The even bigger problem is that given the loose definition of impression, really Internet savvy people could create "impressions" that no human could ever see, like videos playing in the background or fake traffic to sites. (Mike Shields over at AdWeek highlights a perfect example of this practice.)

????All of this low quality and fraudulent impression continues to depress the price quality content producers can get for "real" impressions. Okay, you might say. So what? If there is that much fraud, the value should drop. And that is true, but as the price of the impression drops, quality content companies have three choices:

????1. Load up more and more advertisement impressions into their content (which is bad for consumers, who in turn find a way to avoid, and continues to lower the value of impressions)

????2. Find a way to have consumers pay for content without advertising (HBO, PandoraOne, Netflix, The Information).

????3. Go out of business.