The term ‘id est’ may be unfamiliar to some when written this way. In fact, we see ‘id est’ written frequently as ‘i.e.’ It is usually used to indicate an explanation of something.
‘Id est’ comes from the Latin, meaning is ‘that is.’ The first use of it in spoken or written English is unknown.
‘I.e.’ is frequently confused with ‘e.g.’ This is incorrect; e.g. stands for ‘exempli gratia,’ which literally means ‘for example.’ ‘I.e.’ doesn’t provide an example, but a meaning. The two are frequently mixed up in written English as they are presumed by many to be synonymous.
Aside from this, it has become hard to determine what is proper and improper with ‘i.e.’ as there are a variety of ways in which it is used. In British English, for example, it is standard to place a comma afterwards, whereas American English goes without. It is rare to see the term used entirely incorrectly, as it’s such a common figure of the written and spoken word. It used to be deemed incorrect to put a colon after i.e. – ie: like this – but this is now widely accepted, as is italicising the term.
‘Id est’ is frequently, if not then always, abbreviated to ‘i.e.’ Examples of use in a sentence:
‘I use the browser IE, i.e. Internet Explorer.’ (I’ll get my coat…)
‘Bob’s pets, i.e. his cats, need a bath – they stink.’