commas with introductory elements

Follow the guidelines below in deciding whether to use a comma after an introductory element in a sentence.

Introductory clause

An introductory subordinate clause is normally followed by a comma:

• If you can’t log on to the website, then call the technical help desk.
• Now that the Canadian film industry has come of age, it is time to focus on securing a larger share of the market.

Long introductory phrase

An introductory phrase, especially if it is a long one, is often followed by a comma:

• Of all election issues, the place of minorities in society is the most sensitive.
• Because of the impending storm and the high waves, the race was called off.

Adverbs and short phrases

After introductory adverbs and short phrases indicating time, frequency, location or cause, the comma is omitted unless needed to avoid ambiguity or add emphasis:

• By next week the new budget will have been thoroughly analyzed.

but

• In 1994, 1457 employees started using the new operating system.

However, introductory adverbs or phrases used to mark transition or to express a personal comment are usually set off by commas:

• Nevertheless, the program will go ahead as scheduled.
• In short, no hiring is currently taking place.

Conversely, it is sometimes possible to omit the commas that ordinarily set off non‑restrictive elements, without obscuring the meaning. This is especially true of short adverbial expressions:

• Her words went of course unheeded.
• All the same he had no compunction about slipping the waiter a few dollars to be on the safe side.

In such sentences the addition of commas not strictly needed for clarity gives emphasis to the elements thus enclosed:

• Her words went, of course, unheeded.

Adjectives or participles

The introductory phrase may also consist of an adjective or participle separated from its noun by the definite or indefinite article.

An introductory adjective or participle (or an introductory adjective or participle phrase) is followed by a comma:

• Unprepared, the team was no match for its opponents.
• Clearly upset by the heckling, the speaker stopped for a moment to regain his composure.