Writing Tip : Semicolons and commas: A few simple guidelines

Semicolons and commas: A few simple guidelines

Summary

This article provides some simple punctuation guidelines.

The problem

When writing very short sentences one after the other, an unpleasant stop–start effect can result. For example:

• This is John. This is Kate. This is Sam.
• Sample one worked. Sample two failed.

Joining short sentences together to form a single, longer sentence can avoid this stop–start effect. This is done using a combination of commas, semicolons and joining words like and, or and but.

Four guidelines

Note: In the examples below, "[words]" represents any sequence of words that could stand by themselves as a sentence. For example, "he missed the ball" or "today is Monday".
 
Similarly, "[joining word]" represents a word chosen from the left column.

Rule	Joining words	Punctuation
1.	[none]	[Words] ; [words] .

For example:

• This is John; this is Kate; this is Sam.
• Sample one worked; sample two failed.

 

Rule	Joining words	Punctuation
2.	consequently for example however moreover namely nevertheless otherwise therefore that is thus	[Words] ; [joining word] , [words] .

For example:

• It's just what we need; thus, our search is over!
• Sample one worked; however, sample two failed.
• He missed the ball; therefore, he loses four points.

 

Rule	Joining words	Punctuation
3.	i.e. e.g.	[Words] ; [joining word] [words] .

For example:

• Choose a common name; e.g. John or Mike.
• Sample one worked; i.e. it yielded a positive result.

 

Rule	Joining words	Punctuation
4.	and but for nor or so yet	[Words] , [joining word] [words] .

For example:

• I am Karen, and this is my sister Sue.
• Sample one worked, but sample two failed.
• Today is Monday, so tomorrow is Tuesday.

Notes

You can find more information on the difference between i.e. and e.g. here.
 
Note also that if, as, because and then are usually not preceded by a comma. For example, we write:

• Sample one worked because sample two failed.

not

• Sample one worked, because sample two failed.