Piano theory is all about understanding the music that you play or want to play. It allows you to recognize what is behind the music and how that creates a specific effect for the listener.

Theory covers the notes you play (pitch, scales, chords and melody), how you play them (rhythm, timbre, dynamics, articulation and expression) and how the notes interact (harmony and texture). At the highest level, theory encapsulates how the structure of music creates specific effects, and how you can use notation to understand or communicate written music. See our chapter on learning how to read piano music for more on notation.

Learning theory gives you a wide range of tools that will help you as a musician. Of course, not everyone needs to delve into piano theory, but there are plenty of reasons why it's an excellent idea. So… why should you learn?

To understand why it works

Think of your favourite song. There is something about the way the melodies, harmonies and chords work together to create something you love. Piano theory allows you to break down those elements to understand why they work together. As you progress, you'll start to recognise them in other pieces of music.

For example, the Elvis Presley classic "I Can't Help Falling In Love With You" uses the melody of 1700s French love song "Plaisir d'amour". The Pet Shop Boys' "Go West" - like many other songs - uses the chords of Pachelbel's "Canon in D". Knowing this won't take away the enjoyment. Instead, it allows you to appreciate the beauty of the music on another level, and expand your understanding into new genres.

If your focus is classical music, then piano theory can help unravel pieces like Sonatas, which can seem very long and complex. Once you have some grasp on musical theory ideas of themes and variations, they quickly become easier to understand and you can enjoy Sonatas - and much more - on a whole new level.

To boost your creativity

We've said it before: "You have to know the rules to break the rules." This applies to any art form. Writers need to go deep into their language to push it to the boundaries, while filmmakers study lenses and lighting. Music is no exception. If you know why certain chord progressions, rhythms and textures work, then you can introduce them into your own music. Then you can play around with them to make it something entirely your own.

Most of all, it helps you to avoid all the tropes that have been done before a million times, like "that" four-chord progression used for everything. If you learn music theory, even if you just want to play pop piano, you're joining the ranks of some incredible musicians who are "classically trained": from Elton John, Freddie Mercury and Ray Charles, to Alicia Keys, Annie Lennox and Beyoncé. They all knew the rules and boundaries, then they pushed or broke them to produce something truly amazing.

To unite all instruments

The piano is one of the few instruments where a solo musician can perform full, authentic arrangements of an entire song. On piano, a solo player can recreate bass and treble clef, vocal melody, and more. It's difficult to achieve this range and versatility with other instruments; you'd need an accompanying orchestra or band to replicate the depth and richness you get with the piano alone. 

When you learn the theory behind piano music, it doesn't simply make you a better pianist–it gives you a better understanding and appreciation of all instruments. Scales, rhythms, melodies, harmonies, and chords are universal. So, if you build up knowledge of the theory, then start learning the guitar, flute, or trumpet, you will find that the same principles apply. This can help to accelerate your learning as you move forward.

Plus, it can be incredibly useful if you want to play with other musicians of any kind...

To communicate in a new language

In our chapter on the basics of reading music, we go over the benefits of learning musical notation. All in all, it's a new language that you can use to communicate. With yourself - as a memory aid. With long-gone composers - understanding what to play at a single glance. And with other musicians - taking you beyond musical notation.

Even a small amount of theory can go a long way. For example, learning the names of chords will allow you to instantly communicate which combination of chords make up the song you want to play, allowing bass, rhythm and lead parts to move together. The same goes for learning scales, which is especially useful if you want to start improvising in any kind of group setting. The pentatonic scale - for example - is a great place to start when playing blues, jazz or pop solos on piano or any other instrument.