Comma After Introductory Element

It's important to remember that introductory words and phrases—any words or phrases that come before the main clause in a sentence—should be set off with a comma. Here is an example of a sentence that does not include the required comma and then the correction:

Incorrect (Missing Comma):

In case you were wondering I never allow myself to be exposed to direct sunlight unless I have my scarf, my sunglasses, and a large umbrella.

Correct:

In case you were wondering, I never allow myself to be exposed to direct sunlight unless I have my scarf, my sunglasses, and a large umbrella.

For more information on this comma rule, be sure to check out the Comma section in the Punctuation area of Grammar Essentials.