These are both abbreviations of Latin phrases. Exempli gratia is the long form of e.g. and means ‘by way of example.’ Id est is the long form of i.e. and it means ‘that is.’ Although it’s not a good idea to use foreign phrases in our writing, it helps to know what they mean when we come across them as readers. Here are a few commonly used Latin phrases:

A priori
Already known to be valid; a fact known a priori needs no analysis.

Bona fide
Legitimate; authentic; done or made in good faith.

Carpe diem
Seize the day; enjoy the present.

Caveat emptor
Let the buyer beware.

De facto
According to fact; in reality.

Et cetera
And other things, and so forth; abbreviated as etc.

Inter alia
Among other things.

Ne plus ultra
The utmost point; the acme; perfection; the highest degree of a state or quality.

Non sequitor
An illogical or irrelevant conclusion, or an inference that does not follow from the premise.

Per se
By or in itself; intrinsically.

Nota bene
Take notice; abbreviated as N. B.

Quid pro quo
Something given or taken in return for something else; a substitute.

Sine qua non
Indicating something essential; a necessary element or condition.

Flagrante delicto
In the very act of committing a crime or offense.