CUDA what exactley is it? cuda?

What is CUDA i hear you guys talking about it but dont know what it is ?

CUDA is a compiler/toolkit that allows one to write C code and have it execute on G80 and newer GPUs. NVIDIA wrote PhysX using it and people on this forum are using it for a variety of things. I’m using it to run simulations for my research, others are performing financial model calculations, MRI image processing, video encoding, …

The CUDA Zone has a list of applications and research papers: