What "Security" Even Means (Threat Modeling Basics)

Security is protecting confidentiality, integrity, and availability against people who want your system to break - and threat modeling is just four plain questions that turn that vague worry into a plan.

1. Think Like an Attacker Security means protecting three things - confidentiality, integrity, and availability (the CIA triad) - against people who actively want your system to break; the core skill is shifting from 'does it work?' to 'how could this be abused?'
2. Threat Modeling, Lightly Threat modeling is four plain questions - what are we protecting, who'd attack it and why, how could they get in, and what do we do about it - plus the idea of a trust boundary: the line where data crosses from somewhere you don't control into somewhere you do.
3. Defense in Depth & Least Privilege No single wall is enough, so you build layers (defense in depth); you give every component the minimum access it needs (least privilege); and you assume a breach will happen and design to limit the blast radius - while remembering that obscurity isn't security and humans are the softest target.