E.g. - i.e.
Many younger students - and occasional older ones - confuse the Latin abbreviations e.g. and i.e. Most academics are irritated if you do. Once you have got the difference between them into your head, you will not confuse them again. So make sure to learn the difference.
- e. g. means 'for example'. Use it when you mention one or a few (NOT all) of a large group. (It comes from the Latin phrase exempli gratia, "for the sake of an example".)
- i. e. means 'that is' or 'in other words'. Use it when you want to name all the members of a group, or to explain anything more fully. It comes from the Latin id est = 'that is'. (It is basically a way of introducing an explanation of something you have said - not an illustration of it.)
To illustrate the difference between e.g. and i.e.: consider the United Nations. If you say "... the UN, i.e. ...", you should add the names of all member states of the UN - about 187. If you only want to mention two or three, use e.g. If you want to list all Permanent Members of the Security Council (China, France, Russia, the United States and the United Kingdom), then you should use i.e., not e.g. When you mention "the smaller countries that are members of the UN", e.g. [+ a few names] allows you to stop worrying about the definition of 'small'. 'I.e.' would imply that you should name all the members of the UN that fit your definition of 'small country'.
The writer of a survey carried out in a particular area who sets out as the first item "Write the name of the street where you live,
i.e. Hinderwell Street" has made a mistake in the use of i.e. Obviously the item is intended to seek information - the respondent may live in any one of a number of streets in the area. This would have been properly phrased as "e.g. Hinderwell Street." What has actually been said is "Only those who live in Hinderwell Street are wanted."
Another example shows the confusion that can arise. When an e-mail is sent asking if any tickets are available for a football match, saying "tickets for matches soon after Christmas, please? (i.e. 28 Dec vs Birmingham, 1 Jan vs Sunderland)", the accurate reader knows that the writer only wants tickets for these two games. If he had said "e.g.", he could have meant any game at all in late December or early January.
For a note on punctuating these items, see e.g. - i.e. (punctuation).