OpenCV, or Open Source Computer Vision Library, is a software library that provides a comprehensive set of computer vision algorithms and techniques for image and video processing. It is an open-source platform and is used primarily for developing real-time computer vision applications, including object detection, face recognition, and gesture recognition, among others. OpenCV also supports a range of programming languages, including Python, C++, and Java, making it a flexible and accessible tool for developers and researchers in the computer vision field.