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Frame from CS50 Lecture by Mark Zuckerberg - 7 December 2005 Plays via YouTube's privacy-enhanced embed

CS50 Lecture by Mark Zuckerberg - 7 December 2005

CS50
Lectures
YouTube
2 HN users recommended this lecture2 months2016–2025 score 2
Years with an HN recommendation, 2007–2026

HN commenters mine it for early-Facebook history, such as his view on open source, privacy and the problems that shaped its architecture.

A December 2005 guest lecture by Mark Zuckerberg in Harvard's CS50, discussing Facebook's early days, its technical choices and computer science. It captures him as a 21-year-old founder before Facebook's rise.

“where he walks through the issues they hit early on.” (HN, 2025)

2 recommendations · 7 citations · Lectures

9 Hacker News comments

From the HN archive; up to 20 kept per video, favoring different commenters. Recommendations first.

@syspec Feb 2022 Recommends
on HN thread Mark Zuckerberg on the Lex Fridman Podcast [video]
It's easy to poke fun at Mark because he's mega rich and can come off a little stiff, but he's pretty interesting to listen when he's speaking without a script. Here's Mark when he was 21 giving a lecture at Harvard's CS50: [this video]
Zuckerberg speaking without a script at 21
@alpine01 Oct 2025 Recommends
on HN thread Why is everything so scalable?
Read more
There's a now famous Harvard lecture video on YouTube of Zuckerberg earlier in the Facebook days, where he walks through the issues they hit early on. [this video] I watched it ages ago, but I seem to remember one thing that I liked was that each time they changed the architecture, it was to solve a problem they had, or were beginning to have. They seemed to be staying away from pre-optimization and instead took the approach of tackling problems as they had as they appeared, rather than imagining problems long before/if they occurred. It's a bit like the "perfect is the enemy of done" concept - you could spend 2-3x the time making it much more scalable, but that might have an opportunity cost which weakens you somewhere else or makes it harder/more expensive to maintain and support. Take it with a pinch of salt, but I thought it seemed like quite a good level-headed approach to choosing how to spend time/money early on, when there's a lot of financial/time constraints.
Early Facebook architecture changes driven by actual problems

Citations, criticism and jokes

@danso Jan 2016 Cites it
on HN thread Angular 2 versus React
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> React is a library. It’s precisely the opposite philosophy of large, comprehensive frameworks like Angular and Ember. So when you select React, you’re free to choose modern best-of-breed libraries that solve your problem best. JavaScript moves fast, and React allows you to swap out small pieces of your application for better libraries instead of waiting around and hoping your framework will innovate. Just an aside, but who would've thought that Facebook would be the one to develop around the Unix philosophy? Yes, I know that Google is a monolith, but it became a monolith over one very specific feature and mission, whereas Facebook had to accompany many kinds of user-interaction and behavior right from conception. When Zuckerberg guest lectured CS50 (more than 10 years ago), he didn't foresee FB doing open-source: [this video] Excerpt: "There's a lot of work that goes into making stuff open source. And it's on top of whether or not you want to lose the competitive advantage...there's a lot of support and licensing and all that stuff. We found that it's been annoying" Yes, I know FB of 10 years ago is nothing like it is today, with much different people and components...didn't React arise partly/mostly from Instagram? Either way, I was encouraged to use it early on because it was purportedly being used in Instagram production. Angular 1.x wasn't in any of the big sites (other than DoubleClick?). It's nice to see it in more of Google's sites now...but honestly, how it has currently
Zuckerberg did not foresee Facebook open-sourcing
@zangiku Jul 2017 Cites it
on HN thread 500 Startups admits it kept Australian partner in the dark
The ones that are good at building something (or at least focused on it) won't be wasting their time trying to "give back" (read: find other opportunities). Zuckerberg did some very minimal "giving back" while building Facebook IIRC (the biggest being an actually useful course he visited at Harvard called CS50, here: [this video] )
Zuckerberg guest lecture at Harvard CS50
@danso Nov 2017 Cites it
on HN thread Facebook asks users for nude photos in project to combat revenge porn
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I agree, I don't want to sound like a Zuckerberg apologist, but it's simplistic to view the Zuckerberg and Facebook of today as we would a 19-year-old Zuckerberg and his elaborate PHP script. As a trivial example: In 2005, when Facebook was a non-trivial company, Zuckerberg [0] guest lectured at a Harvard CS50 class. When asked if Facebook would contribute to open-source, he said that he didn't foresee it being worth the trouble (can't find the exact timestamp, so this is all IIRC with a grain of salt). Now of course, open-source is a substantial part of Facebook. Is it because Zuckerberg in the following years had a Road to Damascus experience with Richard Stallman? Maybe, but it's more likely that Facebook evolved into the type of organization where OSS became a benefit to the bottom line, and it was a decision made by people lower than Zuckerberg at that point. Even if Zuckerberg is still as much a creep as he was in private IM messages as a 19-year-old, he's no longer the sole captain of his tiny boat. Him breaking the law means that many people end up getting in legal trouble, i.e. it doesn't really much matter what he alone thinks is moral when he has dozens of people/potential whistleblowers looking over his shoulder with greater moral concerns. [0] [this video]
Zuckerberg's 2005 view on open source
@paulsutter Jul 2022 Cites it
on HN thread Beating the Averages (2001)
But what happens if a company chooses truly the worst language. Like PHP? Oh, right. That was Facebook. They ALSO ran circles around their competitors and crushed them. I hear they are worth /even more/ than Viaweb! Great PHP story: > Dustin was like, 'Hey, I want to help out" > Zuckerberg told Moskovitz, "That's pretty cool. But you don't know any PHP." > "That weekend he went home, bought the book 'PERL for Dummies,' came back, and was like, 'OK, I'm ready to go,'" Zuck said, and told him, "The site's written in PHP, not PERL, dude." - [this video]
Source of PHP story about Moskovitz
@simonh Jul 2022 Cites it
on HN thread Bill Watterson’s refusal to license Calvin and Hobbes (2016)
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I suspect the difference is that in the past the only way to go commercial was to work with a big corporation. Going to market with something was so hugely expensive, and required extensive marketing and distribution infrastructure, which was all internal to these big concerns. The problem was these companies expected a lot of invasive creative control and long term contracts to give access to those capabilities, which to be fair were hugely expensive to build and operate. Nowadays all of that infrastructure exists as generic services on the internet you can throw together in a few days, with costs that scale with your needs. I recently watched a Q&A Mark Zuckerberg gave to the Harvard CS50 class in 2005 [0]. He explained that what made Facebook possible to start with was cheap hosted servers running open source software, and the ways that had changed over the previous decade. Nowadays with AWS and Google Cloud its even easier and cheaper. The same applies to physical goods now with eBay, Amazon Marketplace, Etsy, Shopify, running your own one-person media empire on Youtube, etc. The negative connotations with "selling out" were the fact that you had to sell out creative control. You don't have to do that anymore. Dave Chappelle is rightly still sore about how he was cheated over the Chappelle Show. Nowadays you can build an audience independently, and that fact means that even if you do make a deal with big business, they know you're not as dependent on them anymore, so crea
Cheap hosted servers and open source enabled Facebook
@dusted Jul 2022 Cites it
on HN thread My Criteria for Picking Startup Ideas
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I'd speculate that knowing/discovering/finding the answer to that question is at the very core of why he built the service. I recently watched a 2005 guest lecture[1] by Zuckerberg, it hit me then, why facebook became the success it is/was. The core insight, was the "people you may know" feature, even though that's obvious when I say it, and think about it.. It never struck me before, that, facebook could have been anything (and, was indeed very different back then) and still have succeeded because solving that problem in a seemingly more efficient way at the time then nobody chocked on it. [1] [this video]
Insight about People You May Know as core to success

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