See AI.
Understand how it actually works.
Each topic connects a visual explanation, an interactive mechanism, technical depth and primary sources. Build intuition first, manipulate the mechanism, inspect its limits and then go to the evidence.
Start with one mechanism
What does it mean for a model to reason?
Separate fluent generation from deliberate inference, then connect reasoning traces, reinforcement signals and test-time compute to what the system can actually verify.
Open the complete series 5 chapters →Why 5sigmas?
In particle physics, a result is conventionally treated as a discovery only when it reaches five-sigma significance: a threshold stringent enough that an extreme background fluctuation has a probability of roughly one in 3.5 million under the usual Gaussian interpretation.
5sigmas applies the same editorial instinct to artificial intelligence: separate durable knowledge from daily noise, demand evidence, and build judgment before accepting a narrative, tool or promise.
Choose how to continue
Core concepts
Direct answers to the concepts behind modern AI systems.
Visual explanations
Open the complete path →Choose a path
View all series →Engineering
Proactive and reactive agents and tool calls
How to separate the conversational contract, internal execution and deferred completion without turning conversation history into the system database.
Open the note →