Think of the most valuable thing your favourite app or website holds about you — your photos, messages, payment details, even your location history. Now imagine all of that being exposed or misused. That unsettling thought is exactly why we cannot design systems without treating security, privacy, and ethics as core ingredients, not optional extras. In this chapter, we’ll explore how to keep information safe, respect the people behind the data, and make choices we can be proud of — from the very first sketch all the way to the finished product.