What is the significance of the term "octave" in music theory and how does it relate to the concept of pitch?

In Music Theory, an octave is a musical interval that spans eight notes. It is significant because notes that are an octave apart have the same pitch but differ in frequency. This means they sound similar but one is higher or lower than the other. The concept of pitch refers to how high or low a sound is, and octaves help us understand and organize the relationship between different pitches in music.