You seek to learn algebra online. Two titans dominate the landscape: the free, open champion Khan Academy, and the structured, university-backed Coursera.

Khan Academy: The People's Champion. It offers a massive, comprehensive library of bite-sized videos and practice problems, all for free.

Coursera: The University Powerhouse. It offers structured courses from top universities, often with real professors, deadlines, and certificates.

Khan Academy's strength is its granularity. If you're stuck on one specific skill, you can find a 5-minute video on it.

Coursera's strength is its holistic structure. It takes you on a complete, semester-long journey from start to finish.

Khan Academy is perfect for K-12 students and for supplementing a class you are already taking.

Coursera is ideal for adult learners who want a university-level experience and a credential to show for it.

The weakness of Khan is its lack of a live community or instructor interaction.

The weakness of Coursera can be its cost and the inflexibility of its deadlines.

The Verdict: Use Khan Academy as your ultimate, free textbook and practice tool. Use Coursera when you want the structure and prestige of a formal course.