PixiJS is a lightweight, fast 2D rendering engine for JavaScript. It abstracts WebGL complexity and provides a simple API for drawing, animating, and interacting with 2D graphics. PixiJS uses GPU acceleration to render thousands of sprites, text, graphics, and effects with minimal CPU usage. Core concepts include: Sprites (textured 2D objects), Containers (hierarchical grouping), Graphics (vector drawing), Text (text rendering), and Shaders (custom rendering effects). PixiJS handles event system, transforms, scaling, rotation, alpha blending, and texture caching automatically.