Improved Searching on Your Mac
The macOS High Sierra search capabilities are upgraded with this update. From mail to spotlight you'll see new features.
Spotlight can now connect to the Internet in new ways so that you can see what you want without leaving Spotlight. You can enter a flight number to get departure and arrival times, gate information and more. You can see rich results with information about a wide number of topics in the spotlight search.
In Mail, you'll find Top Hits, which are the messages you are most likely searching for. This takes into account the mail you read, people you reply to, VIPS and more.