xv6 is a modern reimplementation of Sixth Edition Unix in ANSI C for multiprocessor x86 and RISC-V systems. It was created for pedagogical purposes in MIT's Operating System Engineering course in 2006.^[1]

MIT's Operating System Engineering course formerly used the original V6 source code. xv6 was created as a modern replacement, because PDP-11 machines are not widely available and the original operating system was written in archaic pre-ANSI C. Unlike Linux or BSD, xv6 is simple enough to cover in a semester, yet still contains the important concepts and organization of Unix.^[1]

One feature of the Makefile for xv6 is the option to produce a PDF of the entire source code listing in a readable format. The entire printout is only 99 pages, including cross references.^[2] This is reminiscent of the original V6 source code, which was published in a similar form in Lions' Commentary on UNIX 6th Edition, with Source Code.

xv6 has been used in operating systems courses at many universities, including:

• Ben-Gurion University^[3]
• Binghamton University
• CentraleSupélec
• Columbia University^[4]
• Ghulam Ishaq Khan Institute^[5]
• Federico Santa María Technical University
• George Washington University^[6]
• Nile University^[7]
• Georgia Tech^[8]
• IIIT Allahabad
• IIT Bhubaneswar and PEC Chandigarh
• IIT Bombay^[9]
• IIT Delhi
• IIT Madras
• IIIT Delhi
• IIIT Bangalore
• IIIT Hyderabad
• Iran University of Science and Technology^[10]
• Johns Hopkins University^[11]
• Karlsruhe Institute of Technology^[12]
• Linnaeus University^[13]
• Milwaukee School of Engineering
• Motilal Nehru National Institute of Technology Allahabad
• National Taiwan University^[14]
• National University of Córdoba^[15]
• National University of Río Cuarto^[16]
• New York University
• Northeastern University^[17]
• Northwestern University^[18]
• Portland State University^[19]
• Rutgers University^[20]
• Slovak University of Technology in Bratislava^[21]
• Southern Adventist University^[22]
• Stony Brook University^[23]
• Technion – Israel Institute of Technology^[24]
• Tsinghua University^[25]
• Federal University of Minas Gerais^[26]
• University College Dublin^[27]
• University of Belgrade School of Electrical Engineering^[28]
• University of California, Irvine
• University of California, Riverside^[29]
• University of Hyderabad
• University of Illinois at Chicago^[30]
• University of Leeds^[31]
• University of Modena and Reggio Emilia^[32]
• University of Otago^[33]
• University of Palermo^[34]
• University of Pittsburgh^[35]
• University of Strasbourg^[36]
• University of South Florida^[37]
• University of Tehran^[38]
• University of Utah^[39][40]
• University of Virginia^[41]
• University of Wisconsin–Madison^[42]
• University of Kassel
• Yale University^[43]

• Pintos
• Not Another Completely Heuristic Operating System (Nachos)
• Minix
• Xinu