The point cloud data can be defined as a group of data points in some coordinate system. In 3D, it has X, Y, and Z coordinates. PCL library is an open source project for handling 2D/3D image and point clouds processing.
Like OpenCV, it is under BSD license and free for academic and commercial purposes. It is also a cross platform, which has support in Linux, Windows, Mac OS, and Android/iOS.
The library consists of standard algorithms for filtering, segmentation, feature estimation, and so on, which is required to implement different point cloud applications. The main web page of point cloud library is http://pointclouds.org/.
The point cloud data can be acquired by sensors such as Kinect, Asus Xtion Pro, ...