Brand lift
Brand lift measures a campaign's effect on brand metrics - awareness, recall, consideration, intent - usually via surveys comparing exposed and control groups. It is the outcome measurement for upper-funnel activity that conversion metrics cannot see.
In practice
Lift studies need sufficient spend, reach and time to read; underpowered studies produce noise dressed as insight.
Pair lift results with longer-term demand signals like share of search to connect brand activity to commercial trajectory.