Oct. 27, 1994

HotWired, the online version of Wired magazine, runs the first-ever banner ad. "Have you ever clicked your mouse right HERE?" the ad asked. "YOU WILL" it answered. It was right. 44% of people who saw the ad clicked on it, according to Joe McCambley, who was a member of the team which built the ad for AT&T.

June 1995

SmartBanner, the first-ever ad server, is released by two Stanford graduates. Saturn and Intel are among the first clients. Dave Zinman, one of the founders, said a request for a $100,000 seed investment was returned by the Mayfield Fund with a voicemail offering $1 million. And so, the first ad-tech investment was made.

1996

DoubleClick is founded. Fortune called it "an advertising broker that serves both companies with websites and advertisers looking to reach webheads." DoubleClick, the article said, also sells banner ads on member sites, taking 30% to 50% of the revenue. The company's key feature: ad targeting.

1997

The digital-ad world is still "the realm of the young and people that were wacky," according to Denise Zaraya, who worked on early banner ads at Media.com, an agency owned by Grey. Working on banners was also the realm of visionaries, she said. The cost per thousand ad views (CPM) came in at around $10 to $12 back then, according to Ms. Zaraya.

1998

DoubleClick goes public, raises $60 million.

2000

The depth of the dot-com bust leaves the digital advertising industry -- still dominated by banner ads -- in shambles. DoubleClick loses 70% of its clients. "The only thing that saved us is we probably lost 80% of our competitors," its former CEO, Kevin Ryan, told TechCrunch. Ms. Zaraya recalled "pink-slip parties" where fired people would party with their ex-colleagues.

2003

The industry recovers. "There was definitely a time where if you had digital experience, you couldn't get hired fast enough and you could pick any job you wanted," Ms. Zaraya said. At this time, she was international product director at DoubleClick.

2007

Google acquires DoubleClick for $3.1 billion in cash. Yahoo acquires Right Media -- an ad-tech company serving 4 billion ad impressions a day -- for $680 million. Right Media Chief Technology Officer Brian O'Kelley then founds AppNexus, an ad exchange. This is the year automated (programmatic) ad buying became a thing.

2011

AdKeeper, a startup backed by $43 million in venture capital, tries to get people to save, or "keep," banner ads when they're not clicking them.

2012

1.05 trillion banner ads are sold through ad exchange AppNexus. AdKeeper begins shutdown.

2013

Native advertising surges. Some sites, like BuzzFeed, eliminate banner ads altogether. Other websites, such as USAToday, minimize them. The "banner industrial complex" appears to be under threat.

2014

6.2 trillion banner ads (estimated) are sold through ad exchange AppNexus. In August 2014, ads get clicked on .09% of the time, according to Google, a far cry from Mr. McCambley's 44%.