Music theory is a large and varied subject. Beginning your study with the aspects of it that are most useful to you right now is not only the most practical approach, but also will give you the opportunity to practice, explore, and build on what you learn.
Music theory is the study of how sounds are organized so that people recognize them as music. It includes knowledge that is very useful if you want to compose, arrange, or improvise music; or improve your skills as a conductor, singer, or instrumentalist; or be a knowledgeable music historian, musicologist, or music critic.
However, when people organize sounds into music, there are many, many choices to make, at every level from the most basic to the most complex. What timbres count as "musical" sounds? What pitches are they allowed to have? Once a sound is made, what might the next sound be, and when should it be made? When and how can sounds be played at the same time? What makes a group of sounds belong together as a musical idea, and how should musical ideas be organized into longer, more complex pieces?
In addition, there are many, many different styles, genres, and traditions of music in the world, and the things that makes them recognizably different is that they have different rules for how to organize sounds into music, so the theory that explains how to do it is also different. If two types of music are similar, then the same music theory can be used to discuss both, but if they are very different, then it is easier simply to use very different music theories to discuss them.
So, music theory ends up being a large and complex area of study, more a group of subjects than a single subject. Whatever your goals as a musician, music student, or knowledgeable listener, you certainly do not have to understand all of every music theory - nobody ever has! - but there are probably certain parts of music theory that would be of great practical use to you. For example, if you want to be able to improvise jazz solos, then understanding jazz scales, modes and harmonies would be very useful. If you enjoy the Latin styles of ballroom dancing, then learning about the rhythms and meters used in those genres would be useful.
The purpose of this Inquiry into Music: Course Home-style module is to help you:
- Identify the specific music-theory knowledge that would be most helpful to your musical development right now; and
- Create a plan for gaining that knowledge.