In the United Kingdom, the engagement ring is worn, by the woman, on the third finger of the left hand (the ring finger).
In the UK the 29th of February (in a leap year) is said to be the one day (coming round only once every four years) when a woman can propose to her partner.
It is usual for a couple to be engaged for a while before they get married. An engagement is actually an agreement or promise to marry, and also refers to the time between proposal and marriage. During this period, a couple is said to be affianced, engaged to be married, or simply engaged.
- See more at: http://www.learnenglish.de/culture/marriage.html#sthash.dw8gVsh7.dpuf