Key data is standard data that is relevant to the type of content your are promoting, for example, a specific product or service.
Key data performs is used to allow users to refine results when they are browsing our websites, to create specific landing pages of similar products and services, and to communicate key information at a glance on your entry specific pages on our websites.
If you don't complete relevant key data, your content will not be visible if a user refines and you have not answer the question.
For example, take a specifier looking for seating. They search broadly for 'seating' and view all the results. They then limit the results by choosing the material option "stainless steel'. If you manufacture stainless steel seating but have not completed the key data for the attribute 'Material', your entry will not be visible in search results.
So, it's important to complete key data wherever possible to ensure:
You don't lose visibility when a user refines a set of search results
Your content appears in landing pages
Buyers have access to quick facts when they look at your content