In March 2003, I stepped off the PATH train at 23rd and 6th and walked down the block to my new job as a contractor for Poindexter Systems, an "ad tech" company. The Flatiron neighborhood was, much like the internet at the time, hung over from the dot com boom and bust. You had to walk a few blocks to find a Starbucks or get lunch that wasn't from a deli. It was a rough, transitional moment for the digital economy, almost primitive. I had no idea as I stepped into the Poindexter office that I was at the nexus of a revolution in how information, journalism and entertainment are created, distributed and paid for.

Over the next sixteen years I grew up with the ad tech industry. I built companies and invented technologies. I made life-long friends. I learned from extraordinary colleagues and mentors how to lead, how to listen, how to be gentle, and how to be brave. As I look back at it all on my last day at AppNexus, I wanted to share a few thoughts on how far we've come and where I hope things go in the future.

The Flatiron neighborhood that I work in today is dramatically different, full of big brands like Home Depot and Starbucks as well as successful home-grown startups like Shake Shack and Peloton. The internet - really, the world - has changed dramatically too. We have smart phones and social media. The lines between digital and physical are blurring. Governments around the world are realizing that they must confront a society of digital goods, digital fingerprints, digital crimes, all of which operate more or less independently of physical boundaries.

Looking back at these sixteen years in ad tech, I can see our footprints in the sands of internet time. We have participated in the transformation of digital advertising and thus the internet. We have provided billions of dollars to fund content creators, spawned hundreds of innovative businesses around the world, seen thousands of talented people learn and develop in and around the industry we created. There are college papers on advertising auction theory; consent frameworks to protect consumers; blockchain and open source implementations of fundamental advertising technologies. The dramatic changes in the Flatiron and the internet are deeply interwoven with the power of digital advertising to help advertisers find customers, to fund content and services: to be the lifeblood of the internet.

Our creation, programmatic advertising, changed the world. We have made progress toward harnessing the power it unleashed - but there's still much more to do. We must protect the privacy of our citizens and at the same time find a profitable, open business model for journalism. We must prevent the use of advertising as a vector for disinformation, hate, deception, and fraud. We must build diverse, inclusive companies. We must find ways to educate a much broader swath of the population so they can participate in the digital economy. In sum, we must create a better internet - and a better world.

I am grateful for all that I have learned in my ad tech journey. I can't wait to take these learnings and apply them to a new set of challenges.