Spotlight
Convert currencies, temperature, and measurements. Enter a currency—like $, €, or ¥—and an amount, then press Return to get a list of converted values. Or specify a unit of measure for measurement conversions.
Narrow your search. You can include or exclude specific folders, disks, or types of information (such as email or messages) from Spotlight searches. Click Siri & Spotlight in System Settings and go to “Search results” on the right and select or deselect categories you want to include or exclude from your Spotlight results.
Use Siri Suggestions. Siri Suggestions offer info from Wikipedia articles, web search results, news, sports, weather, stocks, movies, and other sources when you search with Spotlight.
If you want Spotlight to search only for items on your iMac, open Search with Spotlight on Mac in the macOS User Guide.