tl;dr:"Postgres stands today as one of the most significant pillars of profound achievement in free software, alongside the likes of Linux and Firefox. PostgreSQL has taken a complex problem and solved it to such an effective degree that all of its competitors are essentially obsolete, perhaps with the exception of SQLite."
tl;dr:"Software projects can, and often should, draw a finish line. Or, if not a finish line, a curve for gradually backing off on feature introduction, raising the threshold of importance by which a new feature is considered." This creates stability.
tl;dr:Software should be (1) robust, handling edge cases, various user inputs (2) Reliable, working for an extended period of time "under design conditions," and outside those conditions too. (3) Stable, not changing in unexpected ways. (4) Simple enough to meet the other 3 goals, nothing more.
tl;dr:C clearly stands out as the "single most important and influential programming language." However, as you work with other languages a tension arises - "you’re stuck either writing bad C code or using poorly-suited tools to interface badly with an otherwise good API."
tl;dr:Two types of changes in open source software inflict trauma on communities. A change where everyone has to overhaul their code to get it to work again, or a change to get code idiomatic again. Drew shows examples of both of these in the Python community.