by Gary Ewer, from “The Essential Secrets of Songwriting” website:
There are many components to successful songs, and not all songs use the same components. A bridge is a good way to extend your song, but how do you know if your song needs a bridge?
A bridge usually sits either between a final verse and a final chorus of a song, or between two final choruses. Its main purpose (usually) is to intensify the energy of a song. But it’s worth really exploring the different kinds of bridges that are possible, and take advantage of the ability a good bridge has to provide a needed variation to the end of your song.
A bridge will generally contain different melodic material and will usually be based on a chord progression that differs from the verse and chorus. Bridges exist nicely in verse-only songs; in that case, they can operate much the same way as a chorus does: the lyrics of a bridge in a verse-only design are often reflective rather than narrative.
Here are some ideas for bridges you might want to consider for your song:
1) Bridge that builds energy. In this case, the lyric of the bridge would be an answer to the comment, “Tell me more about how you’re feeling,” and is probably a more typical use for a bridge. The bridge should begin on a different chord from your verse and chorus. If the song is in a major key, consider starting your bridge with a minor chord. Allow the instrumentation and loudness-level of your music to increase.
2) Bridge that acts as an extension of a verse. This is very common in songs that have no full chorus. Queen’s “Love of My Life” might be a good example of this. The bridge, “You will remember/ When this is blown over/And everything’s all by the way…” is simply a way to extend the text, to add to the emotion of the lyric, and to build the intensity of the bridge as it proceeds. Where bridges will often build energy almost immediately, this type of bridge usually proceeds cautiously out of the verse.
3) Bridge that dissipates energy. Though not as common, a bridge that allows energy to wane can be a welcome relief in songs that are loud and reptitious. You could try variations on this idea by allowing an instrumental version of the verse to be your bridge. Allowing energy to dissipate means allowing the melodic range to descend and the instrumentation to lessen, just in time for a final chorus that really kicks into high gear again.
Remember that a bridge is your way to extend your song, to enhance the emotion of your lyric, and to contour the song’s energy level. Not all songs need a bridge, so don’t feel that your song is incomplete without one.