ago / back / before

Ago and back are used for past times from the present moment:

  • I graduated from high school ten years ago.

    (ten years in the past from today)

  • We sent the package three days ago.

    (three days in the past from today)

  • I moved here about five years back.

    (informal – five years in the past from today)

    Before and earlier are used for past times from another time in the past. Here are some examples:

  • Yesterday I missed my train. I got to the train station at 7:10, but the train had left ten minutes before. (or ten minutes earlier) or ( ten minutes before 7:10yesterday)
  • I was very happy when I got this job last January, because I had lost my previous job six months before. (or six months earlier). or ( six months before last January)