MCP, RAG, Agents, Skills: The New AI Vocabulary in Plain English
Somebody says the agent will use MCP to hit the connector, then RAG over the docs, and the skill handles the rest. Every...
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Tokens and Context Windows, Explained From Zero
You are billed in a unit nobody explained. A token is a countable stand-in for a chunk of text — the word is borrowed fr...
What an LLM Actually Costs You
The rate per million tokens is the one number you cannot change, and the smallest part of the bill. Measured on 102 para...
The Chapter Everyone Skips: 孫子兵法 and the AI Capital War
Business writing quotes 知彼知己 and misquotes it — the received text reads 百戰不殆, not the 百戰百勝 that Sun Tzu expl...
Mean, Median, Mode: The Average Is a Choice, Not a Fact
Three different numbers are all correctly called "the average", and which one gets published changes what a reader concl...
A High R² Does Not Mean the Model Is Right
Anscombe printed one regression summary for four data sets in 1973 and said the features that matter are "invisible if w...
Standard Deviation vs Standard Error: Two Numbers, Two Questions
Mean ± 4.36 and mean ± 0.97 are not two ways of saying the same thing. Altman and Bland assigned each to a different que...
What a 95% Confidence Interval Actually Means
Nearly everyone reads a confidence interval as "there is a 95% probability the true value is in here" — including 59% of...
UUID v4 vs v7 in 2026: v1 Was Never the Sortable One
RFC 9562 replaced RFC 4122 in May 2024, and the advice most codebases still follow did not update with it. UUID v1 is ti...
Decoding a JWT Is Not Verifying It
A decoder shows you the claims; it does not tell you whether to believe them. RFC 7519 §7.2 lists ten validation steps a...
Encoding Is Not Encryption: Base64, Percent-Encoding and the Confusion That Leaks Data
The RFC that defines Base64 says in its own Security Considerations that base encoding "visually hides" a password but "...
Which Hash for What: MD5, SHA-256, and the Password Mistake
"MD5 is broken, so hash your passwords with SHA-256 instead" gets both halves wrong, in opposite directions. What broke...
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