In American writing, a comma is used before and after the phrase, i.e., However, in British writing, a comma is placed before but not after, i.e., Therefore.
When used in the midst of a sentence, i.e. and e.g. are lowercase. Most American style guidelines encourage using a comma after e.g. and i.e. and including periods after each letter, and this is frequently reflected in edited American books and periodicals. However, both the AP and the Chicago manuals also allow leaving out the punctuation when the letters are part of an acronym or trademark.
When they appear in the midst of a sentence, e.g. and i.e. are both lowercase (i.e., like this). In both abbreviations, most American style guidelines require a period after both letters. If your list has more than one item, put a comma after e.g. and between each consecutive example. Otherwise, the reader might think that you're trying to create a series of examples that don't make sense as a unit.
Examples: and i.e.; not e.g.; also etc.
However, some people feel that requiring a comma after e.g. is overly formal. If you follow any other form of English, then you can leave it out. It's up to you whether or not you want to use it.
As for etc., many people include it when using an alphabetized list as a way of indicating more items than can fit on one line. However, if you have enough space, it's not necessary.
Punctuation is frequently overlooked by writers. The abbreviations "i.e." and "e.g." are regarded interrupting words inside a sentence and require punctuation on both sides. Before and after the abbreviation, use a comma or a bracket (parentheses). Abbreviations are defined as short phrases used instead of complete words; therefore, they require punctuation.
Exclamation points are useful in writing to express emotion. Exclamation points are used before exclamatory words such as "Oh!" "Ahhh!" and "Gosh!" They add impact to your letter, making it more interesting to read. Avoid using exclamation points all the time, however; otherwise, your letter will seem overly emotional.
Question marks are used to ask questions. Question marks should be placed at the beginning of sentences that contain question words such as who, what, when, where, why, and how. Using question marks correctly adds interest and clarity to your letter.
Commas are used to separate items within a list. Commas are also required before the conjunction word but, and after prepositions such as from, like, when, wherever, and whoever. Without commas, these items are interpreted as one continuous statement which can cause confusion during reading.
Semicolons are used to join two independent clauses into one sentence. Two independent clauses are sentences that describe separate ideas.
In a sentence, the abbreviation "i.e." should always occur with a lowercase I and a lowercase "e," separated by a period. It should not be italicized or bolded. The abbreviation "i.e." does not require a different format than the remainder of the document or paper.
In American English, commas and periods always go within quote marks; dashes, colons, and semicolons almost always go outside; while question marks and exclamation marks sometimes go inside and sometimes stay outside. You should follow this rule unless doing so would be inconsistent or confusing.
If a writer feels the need to utilize it, it should be placed in parentheses: Winston Churchill frequently mentioned his "black dog" (i.e., his gloomy periods). Writers use it to provide specific instances of the issue at hand, for example. It is an acceptable practice to use italics or other means of emphasis instead.
After a comma, you write a capital letter only if the term has a capital letter rule, such as a proper name or the word I. Otherwise, lower the case of the term following the comma.