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ai/rag-how-a-chatbot-looks-things-up-before-it-answers.md RAG: how a chatbot looks things up before it answers A chatbot has never read your shop's rules, so when you ask it about them it may guess, and a confident wrong guess is called a… 5 min read · 3 Nov software-design/feature-flags-how-to-ship-code-switched-off-and-turn-it-on-for-10-of-u.md Feature flags: how to ship code switched off and turn it on for 10% of users A feature flag is a yes/no setting your code checks before choosing between old and new behaviour, so you can ship code switched off and… 5 min read · 2 Nov ai/accuracy-why-a-spam-filter-that-is-99-right-can-still-catch-nothing.md Accuracy: why a spam filter that is 99% right can still catch nothing A spam filter that never flags anything can score 99% accuracy when only 1 email in 100 is spam. So what should you measure instead? This… 6 min read · 31 Oct databases/the-n-1-query-problem-why-a-page-that-asks-the-database-501-questions.md The N+1 query problem: why a page that asks the database 501 questions is slow A page that lists authors and their books can quietly send one query per author. With 500 authors that is 501 trips to the database, and… 4 min read · 26 Oct web/flexbox-how-a-row-of-boxes-decides-who-gets-the-leftover-space.md Flexbox: how a row of boxes decides who gets the leftover space Put three boxes in a row and the browser decides, by a short fixed recipe, who gets the extra room and who gives some up. Learn the three… 6 min read · 26 Oct ai/gradient-descent-how-a-computer-learns-a-number-by-rolling-downhill.md Gradient descent: how a computer learns a number by rolling downhill How does a computer learn a number? It can't solve for it in one go. It tries a guess, measures how wrong it is, and nudges the guess… 5 min read · 21 Oct infrastructure/percentiles-why-an-average-response-time-of-235-ms-can-hide-users-wait.md Percentiles: why an average response time of 235 ms can hide users waiting 3 seconds Your dashboard says the average response time is 235 milliseconds, yet some users wait three seconds. Both can be true, because an average… 4 min read · 21 Oct ai/embeddings-how-a-computer-knows-a-pony-is-closer-to-a-horse-than-a-tru.md Embeddings: how a computer knows a pony is closer to a horse than a truck A computer sees the letters in "pony" and nothing else, yet search boxes can still tell that a pony is closer to a horse than to a truck… 5 min read · 18 Oct ai/temperature-why-a-chatbot-answers-differently-each-time.md Temperature: why a chatbot answers differently each time Ask a chatbot the same question twice and the answers can differ. That is not a bug: the model chooses each next word using chance, and a… 5 min read · 12 Oct ai/overfitting-why-a-perfect-score-on-practice-questions-can-still-fail.md Overfitting: why a perfect score on practice questions can still fail A model that scores perfectly on the examples it learned from can still fail badly on new ones. That failure is called overfitting, and you… 6 min read · 9 Oct networks/latency-vs-bandwidth-why-a-faster-plan-can-t-speed-up-a-small-page.md Latency vs bandwidth: why a faster plan can't speed up a small page You upgraded to a much faster internet plan, yet a small web page loads just as slowly. Why? Network speed is two different numbers… 5 min read · 8 Oct ai/embeddings-how-a-computer-measures-that-a-kitten-is-like-a-cat.md Embeddings: how a computer measures that a kitten is like a cat How does a computer know that kitten is closer to cat than to car? It can't read meaning, but it can measure it. An embedding turns a word… 4 min read · 3 Oct