Bitsets, also called bitmaps, are commonly used as fast data structures. Unfortunately, they can use too much memory. To compensate, we often use compressed bitmaps. Roaring bitmaps are compressed bitmaps which tend to outperform conventional compressed bitmaps such as WAH, EWAH or Concise.

The Common UNIX Printing System (or CUPS(tm)) is a printing system and general replacement for lpd and the like. It supports the Internet Printing Protocol (IPP), and has its own filtering driver model for handling various document types.

libcomerr is an attempt to present a common error-handling mechanism to manipulate the most common form of error code in a fashion that does not have the problems identified with mechanisms commonly in use.

The ext2, ext3 and ext4 file systems are successors of the original ext ("extended") file system. They are the main file system types used for hard disks on Debian and other Linux systems.

Dislocker has been designed to read BitLocker encrypted partitions under a Linux system. The driver used to read volumes encrypted in Windows system versions of the Vista to 10 and BitLocker-To-Go encrypted partitions, that's USB/FAT32 partitions.

Clang project is a C, C++, Objective C and Objective C++ front-end based on the LLVM compiler. Its goal is to offer a replacement to the GNU Compiler Collection (GCC).