Īrnold is based on the Monte Carlo Path Tracing algorithm, making extensive use of importance sampling and other numerical techniques to improve the quality of rendered images. It has a fully programmable API, and uses shaders written in C++ or Open Shading Language to define the materials and textures. It can render large numbers of high-resolution texture maps thanks to its integration of the OpenImageIO library. For complex scenes such as the space station in Elysium, it makes heavy use of geometry instancing, which helps it render trillions of visible polygons in a reasonable amount of memory. It often uses multiple levels of diffuse and specular inter-reflection so that light can bounce off of a wall or other object and indirectly illuminate a subject.

Its ray tracing engine is optimized to send billions of spatially incoherent rays throughout a 3D scene composed of geometric primitives including polygons, hair splines, and volumes. Since March 2019 it supports Nvidia RTX-powered GPUs through the use of OptiX. Originally written in C99 and progressively rewritten in C++, Arnold runs natively on x86 CPUs, where it tries to take advantage of all available threads and SIMD lanes for optimal parallelism. Notable television series include Game of Thrones, Westworld, Trollhunters, LOVE DEATH + ROBOTS and The Mandalorian. Notable feature films that have used Arnold include Monster House, Cloudy with a Chance of Meatballs, Alice in Wonderland, Thor, Captain America, X-Men: First Class, The Avengers, Space Pirate Captain Harlock, Elysium, Pacific Rim, Gravity, Guardians of the Galaxy, Star Wars: The Force Awakens, Arrival and Blade Runner 2049. Created in Spain by Marcos Fajardo and later co-developed by his company Solid Angle SL (now owned by Autodesk) and Sony Pictures Imageworks, Arnold is one of the most widely used photorealistic rendering systems in computer graphics worldwide, particularly in animation and VFX for film and TV.

Arnold is a computer program for rendering three-dimensional, computer-generated scenes using unbiased, physically-based, Monte Carlo path tracing techniques.

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