yes a bridge ties the verses together
When deciding on a Primary bridge, think of the following.
1. What is the structure of my lyric Ex. Verse/ chorus, etc.
2. What has my lyric been saying and have i covered everything. Or, do I need to say more in the lyric.
3. If I do write a bridge, how can the bridge help to show a different point of view or angle to the lyric.
4. Do I need a bridge? Would it musically help to take the song somewhere else.
When to use a Primary bridge ?
This is where a lot of people fail
A bridge is just like the name. It takes you from ONE PLACE over to the NEXT PLACE.
But to do that musically, the listener has to be somewhere before they can cross over to somewhere else.
A Primary Bridge should come after 2 chorus or 2 refrains. I have seen people try and put a bridge after the first chorus. It WONT sound like a bridge, simply because the listener hasnt established where they are yet. A Primary Bridge after the first chorus will sound like another verse.
Now dont confuse a PRIMARY BRIDGE with a B section or a transitional bridge or some call it a pre-chorus. These sections function differently. They can come after a verse to build tension to the chorus or refrain. A primary bridge function is to shed another point of view or twist on the story. It is used to CLEAR UP anything that hasnt been cleared up yet in the lyric, etc. But remember the Primary Bridge comes after the listener has heard the chorus twice or refrain twice.