Introduction to Computer Science by Harvard: A Free Online Course

CS50x (Compuer Science 50) is Harvard University's introduction to the intellectual enterprises of computer science and the art of programming for majors and non-majors alike, with or without prior programming experience. It is an entry-level course taught by David J. Malan. CS50x 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. As of Fall 2016, the on-campus version of CS50x, CS50, was Harvard's largest course. Students who earn a satisfactory score on 9 problem sets (i.e.programming assignments) and a final project are eligible for a certificate. This is a self-paced course–you may take CS50x on your own schedule.

Read about where and how to take this course by clicking on the link