????現如今幾乎瀏覽任何網頁，隨著頁面加載都會出現廣告。但你可能并不知道，這些廣告很多都不是預先設定的——廣告主贏得這一廣告位完全是在你點擊和打開網頁的1/4秒內，也就是幾乎瞬間競價的結果。

????隨著通過實時競價發布的互聯網廣告數量增勢迅猛，谷歌（Google）已將實時競價列為其廣告體系的核心業務。但規模遠小于谷歌的AppNexus卻通過效仿谷歌，也已成為這一領域的領跑者。

????AppNexus的首席執行官兼共同創始人布萊恩?奧凱利最初設立該公司是為了拓寬他在Right Media【2007年該公司已售予雅虎（Yahoo）】開發的互聯網廣告交易平臺，提供一個可兼容各類互聯網廣告交易軟件平臺的開放性市場。

????廣告交易平臺的建立是為了解決互聯網廣告銷售面臨的一個主要問題：由于買賣雙方的時間不一定總能匹配，很多廣告庫存（即互聯網廣告位）白白浪費了。美國市場研究公司eMarketer的分析師勞倫?費希爾稱，第一步是要匯總大批網站可供的廣告庫存。在此基礎上，形成最基礎的交易平臺，擴大廣告銷售規模，由此，實時交易平臺如今已成長為互聯網廣告行業新的有生力量。

????谷歌和AppNexus都一頭扎進了這一領域，但兩者的道路自然不太一樣。奧凱利回憶稱，他最早為AppNexus尋找投資者時，大部分硅谷風投公司還不怎么愿意投資總部位于紐約的初創企業——雖然AppNexus后來得到了“超級天使投資人”羅恩?康威、風險投資公司Venrock和First Round Capital以及其他方面的支持。相比之下，谷歌則擁有足夠的內部資源來打造這塊新業務，它憑借自身在互聯網領域的廣泛涉足和一些大刀闊斧的收購（從2007年收購網絡廣告服務商DoubleClick到去年收購在線廣告平臺Admeld），已在實時競價領域實現了迅速擴張。

良性競爭

????但如果向廣告科技界人士提起實時廣告交易平臺，你可能會同時聽到這兩家公司的名字。在谷歌展示廣告副總裁尼爾?莫漢看來，實時廣告交易平臺是谷歌實現端對端廣告解決方案的“關鍵一環”。據他介紹，谷歌交易平臺去年增長了150%，其中不少銷售額都來自谷歌網絡以及DoubleClick等其他廣告管理公司的客戶。

????谷歌在互聯網展示廣告領域無所不在——許多在互聯網廣告細分領域與這個搜索巨頭競爭的小公司本身也是谷歌的客戶。莫漢稱，谷歌的目標是要消除不同廣告技術之間的摩擦，讓這一過程對所有人都變得更加容易，哪怕他們有時候同時也是競爭對手。

????數字媒體交易公司MediaMath就是一家受益于谷歌“開放式”策略的公司，它提供的平臺服務于希望購買廣告位的營銷人員，采用的供應商則包括谷歌、AppNexus等。MediaMath首席執行官喬?扎瓦德茲基稱，AppNexus有望在谷歌擅長的開放式平臺領域實現趕超。

????When you visit just about any website these days, ads appear as the site loads. But what you can't see is that many of those ads were not predestined for your eyes -- advertisers won the spots in near-instantaneous auctions occurring in the quarter of a second between click and use of the site.

????Real-time online advertising through such auctions is a rapidly growing business, and Google (GOOG) has made it a critical part of its advertising ecosystem. But the far smaller AppNexus has emerged as another leader by taking a page out of Google's playbook.

????AppNexus is a product of CEO and co-founder Brian O'Kelley's goal of broadening the online ad exchange platform that he developed with Right Media (which he sold to Yahoo (YHOO) in 2007) to offer an open market that works across the gamut of software platforms that companies use to buy and sell online ads.

????The ad exchange itself emerged to solve one of the major problems of online ad sales: much ad inventory (spaces where ads appear online) would go unsold as buyers and sellers couldn't always match up in time. The first step was for companies to aggregate their available ad across a swath of sites, says eMarketer analyst Lauren Fisher. From there, basic exchanges emerged, increasing the scale of ad sales, and real-time exchanges have become the latest turn of the wheel.

????Google and AppNexus both plunged into that space but, unsurprisingly, their paths have not been so similar. O'Kelley recalls that when he was first seeking investors for AppNexus, Silicon Valley venture capital was largely steering clear of New York-based startups -- although the company would receive backing from "super angel" Ron Conway, Venrock, First Round Capital, and others. Google, on the other hand, had the resources to build from within, and has grown rapidly in the advertising space thanks to its extensive reach on the web and some aggressive acquisitions, from DoubleClick in 2007 to Admeld last year.

Cordial competitors?

????But ask members of the ad tech space about real-time ad exchanges, and you'll probably hear both companies mentioned in the same breath. For Google, the exchange is "one key piece of the puzzle" in producing an end-to-end advertising solution, according to Neal Mohan, vice president of display advertising. Google's exchange has grown 150% in the last year, Mohan says, with much of the sales from within its own network and clients of other ad managers like DoubleClick.

????In online display ads, Google is everywhere -- and many small companies that compete with the search giant in one cross-section of the online ad world are themselves Google customers. Google's goal, Mohan says, is to cut out the friction between different ad technologies, making the process easier for everyone, even those sometime-competitors.

????One company that is taking advantage of Google's "open" approach is MediaMath, which offers a platform catered to marketers who want to buy ad space, using several suppliers including Google and AppNexus. MediaMath CEO Joe Zawadzki says that AppNexus might be beating Google at its own open-platform game.