Article: Some colleges and universities publish lectures online for free. This is a great way to find a lesson taught by a professional without having to pay the cost. Explore a website like Coursera, an online learning platform that partners with universities and organizations to provide lessons run by top educators. They offer dozens of music theory courses from universities around the world: https://www.coursera.org/courses?query=music%20theory iTunes University is another great resource for finding lectures from accredited universities. The great thing about learning on YouTube is the visual aspect of the platform. If you are a visual or audio learner, finding videos about music theory on YouTube is a great option. A good place to start is Michael New's YouTube channel, which has thorough and straightforward lessons that are easy for beginners to understand as well as advanced content for intermediate to experienced musicians. You might start with his "Music Theory Fundamentals" playlist: https://www.youtube.com/playlist?list=PL1302D94F247600CD There are dozens of websites that are completely devoted to teaching music theory for free. Some of these feature written text, some offer games, and others offer video lessons. Spend some time exploring MusicTheory.net. This website offers clear instruction and has a whole section devoted to interactive exercises: https://www.musictheory.net/exercises Ableton's "Learning Music" course is a great option for people who know nothing about music theory. This interactive website starts with super basic information and allows you to ease into learning music theory: https://learningmusic.ableton.com/ The benefit of using free resources to learn about music theory is that you don't have to buy into just one. Keep trying sites until you find a few that you really like.

What is a summary?
Try a free university-affiliated course on music theory. Use YouTube to find dynamic music theory lessons for free. Read through a few free music theory websites to find one that you like.