comma before 'depending on' [preposition]: are required, depending on


New Member

Could someone explain why a comma is used in the first of the following sentences but not the second?

“Certifications are usually required, depending on the systems used by a particular manufacturer.”

“The price of platinum will rise or fall depending on several distinct factors.”

Assuming my comma usage in the previous two sentences is correct (if I'm mistaken, this will make for a very short answer!), why does one sentence use a comma before "depending" and the other doesn't? What rule governs these examples?

  • In the first case the words after the comma are additional to the main point.

    In the second case the words after "depending" are central to the meaning.
    Just as a slight addition: I've noticed that people commonly use a comma in a place where they would pause slightly if they were actually saying the sentence; whether this is correct would naturally vary slightly from sentence to sentence (and person to person) but it can seem to make the sentence flow more naturally in the mind of the person who wrote it.
    Merely an observation - not a tested theory!
    Rise or fall depending on ... Two choices:
    (1) Rise
    (2) Fall

    Usually required, depending on ... Two choices:
    (1) Required
    (2) Not required

    The comma in the first sentence warns the reader that what the modifier "depending on ..." modifies is not immediately evident but can be inferred from the context.

    The second sentence does not need a comma because the choice is explicitly given just before the phrase that modifies it. In other words, the modifier is next to what it modifies, and they are part of one phrase.