The acronym i.e is the abbreviation for ''id est''. Id est is a Latin word which means 'That is' in English. The acronym is probably one of the shortest I have seen in English language. If you have not used this before, you should use it after reading this.
The acronym is used to expatiate or to give more information about something that's being discussed. The acronym is so much useful when writing articles, letter and the likes. When you are trying to pass an information to someone but you still want the person to get more details about what you are saying, then you use 'i.e' which means 'that is'.
For example, I may decide to use i.e in this way. Hello everybody, John has been nominated for the program i.e he would be the one to represent our school. By this example, I have adequately given more information about what John is going to do at the program.