Pre-chorus is used to bridge the gap between verse and chorus.

Examples:

• Could be used to transition between a soft verse and a loud chorus
• Could be used to increase the anxiety leading up to the chorus

Pre-choruses tend to not be near or on the root note. Will instead normally be around the mid-range.

The pre-chorus can be used to explain the situation leading up to the chorus. For example, in my track, it could talk about the pain and how much it hurts before the chorus talks about how things will never change.

Homework: Try to write a pre-chorus