Tension and Release
Tension and release is another common technique used in music to weave a tale. Tension and release help to build plotline in music through a series of ups and downs, conflicts and resolutions. It can be achieved through harmony, through rhythm, or through a combination of both. Melody can assist in this, but on its own, it does not invoke tension and release with the same efficacy.
Tension may build over the course of a chord progression. Depending on the piece, tense chordal movements may be long-winded or brief. Release often occurs at cadential points. Therefore, release usually comes in the form of major or minor chords. Tonic (I or i) chords are especially good releasers. They may or may not have extensions added to them; it depends on context, period, and style of music. Extensions (such as major sevenths and ninths) will make the release less resounding but they do not hinder the objective, which is an easing of tension.
Must I always use climactic build-ups in my music?Yes and no. You should employ tension and release, including climaxes most of the time and in varying degree. However, it's not absolutely necessary. Certain styles such as serialism, minimalism, ambient music, and liturgical music do not contain strong elements of tension and release. And on occasion, static pieces can be successful too (e.g., Erik Satie's slow and doleful Trois Gymnopédies).
Tension comes from dissonance. It could be argued that a V7 chord provides tension, which is then relieved by a I or vi chord. However, the tension between a V7 – I or a V7 – vi cadence is light: to modern ears anyway. Therefore, simple cadences like this might be better described as an anticipation. Greater dissonance is needed to invoke a more potent version of tension and release. In the aforementioned case, you would alter the V7 chord to make it more pronounced, harmonically unstable, and tense.
Ultimately, tension and release is much more arresting when the tension is built up over the course of many measures. In other words, tension becomes more musically valuable when it climaxes to a veritable breaking point. When you compose music, use tension and release where applicable. It will make your musical story much more expressive, expansive, and memorable.