This is CS50.

Introduction to Computer Science I

Harvard College
David J. Malan, Instructor
Introduction to the intellectual enterprises of computer science and the art of programming. This course teaches students how to think algorithmically and solve problems efficiently. Topics include abstraction, algorithms, data structures, encapsulation, resource management, security, software engineering, and web development. Languages include C, Python, SQL, and JavaScript plus CSS and HTML. Problem sets inspired by real-world domains of biology, cryptography, finance, forensics, and gaming. Designed for concentrators and non-concentrators alike, with or without prior programming experience.

This is CS50 OpenCourseware.

Computer Science 50 (otherwise known as CS50) is Harvard College's introductory course for majors and non-majors alike, a one-semester amalgam of courses generally known as CS1 and CS2 taught mostly in C.

Even if you are not a student at Harvard, you are welcome to "take" this course via by following along via the Internet. (The course's own website is at Available at right are videos of lectures, walkthroughs, and seminars along with PDFs of all handouts. Also available at right are the course's problem sets.

If you're a teacher, you are welcome to adopt or adapt these materials for your own course, per the license.

If you'd like to take this course for real (on Harvard's campus or via the Internet) in order to receive feedback on work, grades, and a transcript, the course will next be offered through Harvard Extension School (as "Computer Science E-50") in Fall 2013; you can register online starting in July 2013. You can also take this course through edX.

Special thanks to Doug Lloyd '09, Rob Bowden '13, Maria Zlatkova '18, and Walter Martin '18, Fall 2016's heads.


Creative Commons License

Copyright © 2015 – 2017, David J. Malan of Harvard University

This course's content is licensed by David J. Malan of Harvard University under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License, which means that you are not only welcome to "take" this course,

you are free:

  • to Share — to copy, distribute, and transmit this content
  • to Remix — to adapt this content
under the following conditions:
  • Attribution — You must attribute this content to David J. Malan of Harvard University but not in any way that suggests endorsement of you or your use of the work.
  • Noncommercial — You may not use this content for commercial purposes.
  • Share Alike — If you alter, transform, or build upon this work, you may distribute the resulting work only under the same or similar license to this one.
with the understanding that:
  • Waiver — Any of the above conditions can be waived if you get permission from David J. Malan of Harvard University
  • Other Rights — In no way are any of the following rights affected by the license:
    • Your fair dealing or fair use rights;
    • Apart from the remix rights granted under this license, the author's moral rights;
    • Rights other persons may have either in the work itself or in how the work is used, such as publicity or privacy rights.
  • Notice — For any reuse or distribution, you must make clear to others the license terms of this work. The best way to do this is with a link to

So that folks (like you!) have a place to turn with questions, we've created a Google Group called cs50-discuss, which is like a message board and mailing list rolled into one.

Once you've joined, you'll be able to email the group at and browse past discussions at!forum/cs50-discuss.