Teams often have straight-forward numbers they would like to hit. Target Key Results sets a hard amount for a goal to climb towards. Success is easily defined by whether the number is met or surpassed.
Target Key Results are best implemented for metrics that require a slower uphill climb.
A few Target examples:
Google Analytics: 22,000 Unique Users
Shopify: $1,500,000 Net Sales
Facebook Ads: 50,000 Click Throughs
The Office: 9,000 reams of paper sold by Dwight Schrute