Nowadays an engagement is a much less formal event than it used to be. It is still a very important commitment, yet unlike marriage, law does not sanction it. This however does not mean that there are no formalities and courtesies that should be observed.
Close family members and friends have to be informed. The parents should be the first to know; they are entitled this courtesy even though it is no longer necessary to ask their consent. Some parents might be old-fashioned and would appreciate some kind, even if mild, gesture pointing towards asking for approval.
Traditionally, the bride’s parents are the first to be told, followed by the groom’s parents. Close relatives and friends come next. In the past it was a common practice to publish announcements in local newspapers but nowadays many resort to social media to spread the news. Make sure that before doing so the closest persons to you get to know beforehand. They will not appreciate getting to know the news through Facebook!