by / until

When talking about a date in the future…

Use by if a single event will happen before that point:

  • I will send you the information by Friday. (= before Friday)

    Use until if a continuous event will continue and then stop at that point:

  • ur guests will arrive by 6:00. (= before 6:00)
  • I’ll be working on the project until Friday. or ( continuously until Friday; I will stop working on Friday)
  • Our guests will stay until 9:00. or ( continuously until 9:00; they will leave at 9:00)