How can I hide search results until the user submits the exposed form? I have a fairly straightforward view, which exposes a simple keyword filter to the user.

Currently, when I first land on the page containing this view, all records are displayed (i.e., the search results are unfiltered).

How can I alter this behavior, so that no search results are displayed until the user has entered a keyword and submitted the form?

(I'm converting an old Drupal 7 site to Drupal 8. On the D7 site, the view does not show search results when I first land on the page. Is this a difference in behavior between the Views implementation in D7 and D8? I can't find anything in the D7 site to suggest that this difference in behavior is caused by a module.)
You can change that under Advanced Views options (third column): Exposed form style:



After you choose Input required, you can adjust further options, including the text to display before any filters are active: 





If you're using Better Exposed Filters module it has an option for it too: 


  Input required
  Only display results after the user has selected a
  filter option.




It hasn't changed since D7, it works the same in D8 as it did in D7.