The ampersand (&) symbol represents the concatenation operator. You can use it to join strings:

  • Q: "now" & "then"
  • A: nowthen

and to create time ranges:

  • Q: now & day
  • A: Mon, 04 Apr 2016 22:13:27 +0200 to Tue, 05 Apr 2016 22:13:27 +0200

While in the first example "now" represents a string, because it is enclosed in double quotes, in the second example now is a relevance keyword that you can use to extract the current time and date from the system clock.