On Twitter, @tveskov asks, how many layers of abstraction does it take to run Twitter.
This is a really hard question, probably intractable - if you want to include the physics and signalling of lasers through the fiberoptic cables that sends Twitter's data to my home. There are simply too many different places along the route where the platform relies on some level of abstraction and comprehension, to do a full enumeration.
Instead, let's tackle a simpler question: How many technologies/abstractions are directly visible in Twitter's source code. I did a view source and tried to find all the technology that I could see from the source would be in use to run Twitter.
The rule here is that it there has to be text in the source file that does not make sense unless I know the abstraction/standard/software/API I'm referring to below.
Here my best shot at the list (in order of discovery (by me, while reading))
Notably absent: The email standards. While obviously employed by twitter (as are many other standards if the API is considered), I found no evidence of email in the source of the logged in front page.