The LAS format is intended as an interchange format for laser scanner point cloud data. It is maintained by the American Society for Photogrammetry and Remote Sensing and at the time of writing is at version 1.4. The format is binary, for efficiency, and the LAZ variant is a losslessly compressed version.
The format is open source and fully documented. An API for programmers as well as a number of useful tools for managing and extracting data from LAS and LAZ files can be found in the "LAStools".
The LAS format uses four types of records, as described below. The files are little endian and contents is binary encoded.
The mandatory single header block contains a file signature (LASF), basic metadata identifying the project, number and type of point data records, dimensions of x,y,z range included, and pointers to the major sections of the file.
Optional Variable Length Records (VLRs) contain variable types of data including projection information, metadata, waveform packet information, and user application data. VLRs are limited to a data payload of 65,535 bytes.
Point Data Records form the primary content of the file. LAS 1.4 defines types 0 through 10 for types of point data. All point records in a file must be of the same type. See Notes below.