Ray tracing is a rendering method that mimics how light actually works in the physical world. Instead of using simplified lighting approximations, the graphics processor calculates the path of individual light rays as they bounce between objects, reflecting, refracting, and casting shadows with genuine accuracy.
Traditional graphics engines use 'rasterisation', which is fast but produces flatter lighting and unrealistic reflections. Ray tracing computes light rays mathematically, so reflections appear in windows and puddles, shadows fall naturally, and materials behave like their real-world equivalents. A mirror reflects exactly what should be visible. Water refracts light the way water actually does.
The catch: ray tracing demands enormous computational power. A single frame might require billions of light ray calculations. That's why it only became practical for consumer graphics cards in recent years, thanks to dedicated hardware accelerators (like Nvidia's RT cores or AMD's Ray Accelerators) that handle these calculations separately from regular graphics processing.
Real-world example: In a game, sunlight streams through a stained-glass window. With rasterisation, the coloured light might look painted on. With ray tracing, the light actually refracts through the glass geometry, casts coloured shadows on the floor, and bounces between nearby surfaces realistically.
When shopping for a gaming PC or graphics card, check whether it has ray tracing hardware if photorealistic visuals matter to you. Many modern games offer ray tracing as an optional graphics setting. Performance does drop with ray tracing enabled, so balance it against frame rates. Entry-level cards may support ray tracing but deliver choppy gameplay if you enable it fully.