If I had to teach this in one paragraph, I would start here: the easiest stories to recall are not automatically the most probable ones. Core idea: Availability bias pushes recent or vivid information to the front of the mind, even when base rates say it should not dominate the decision. Why it matters: That matters in investing because headlines are optimized for recall, not for calibration. In real life: One spectacular blow-up can distort how you size an otherwise ordinary risk if you do not reset back to base-rate thinking. Common slip: The mistake is confusing mental accessibility with true frequency. Try this: If you had to teach this without jargon, what would you tell someone to monitor first? A lot of confusion disappears once you separate the headline from the mechanism.