In sentences like these below, what part of speech or what grammatical function does "by" serve?

  • Open the door BY turning your key.
  • Lift the bucket BY pulling on the rope.

3 Answers 3


Macmillan perhaps realises the peripherality of the use of a preposition followed by an ing-clause.

by [preposition] ...

2 used for saying how something is done

a. using a particular method to achieve something

  • Reading is taught by traditional methods here.
  • The palace balcony is shielded by bulletproof glass.
  • Every bit of lace is made by hand (=not using a machine).

by doing something:

  • By using the Internet you can do your shopping from home.

by post/phone/fax etc:

  • They exchanged New Year’s greetings by email.

They seem to indicate by their bolding that '[by phone]' etc and '[by using] the Internet' etc are at least on the way to becoming idioms, with more coherence than the usual POS analysis can happily deal with. Though to be fair, 'by hand', which is at least as coherent, does not get the offsetting of bolding.

The 'by + ing-group' as an adverbial of method / agency / instrumentality / enabling is of course extremely common. There may or may not be an obvious verbal involvement:

An English Grammar for High School lumps all such ing-forms under the inadequate term 'gerunds' (and the even woolier 'a noun or its equivalent); however, I think the following is useful:

  1. A preposition is a word joined to a noun or its equivalent to make up a qualifying or an adverbial phrase, and to show the relation between its object and the word modified.

  2. Besides nouns, prepositions may have as objects—

(1) Pronouns: "Upon them with the lance;" "With whom I traverse earth."

(2) Adjectives: "On high the winds lift up their voices."

(3) Adverbs: "If I live wholly from within;" "Had it not been for the sea from aft."

(4) Phrases: "Everything came to her from on high;" "From of old they had been zealous worshipers."

(5) Infinitives: "The queen now scarce spoke to him save to convey some necessary command for her service."

(6) Gerunds: "They shrink from inflicting what they threaten;" "He is not content with shining on great occasions."

(7) Clauses: "Each soldier eye shall brightly turn / To where thy sky-born glories burn."

(Of course, some extend 'its equivalent' to mean a retrievable (sometimes even this is dubious) prepositional object, with 'intransitive prepositions'.)


So, if one insisted on forcing it into some class, it would have to be the widely disparate class preposition.


The Cambridge English Dictionary (online) gives two related definitions of the preposition by which are relevant to your examples. They are: agency (explaining by whom or by what an action is caused - in short, the agent); and method Explaining how and action is accomplished.

You can find the definitions and plenty of examples here: https://dictionary.cambridge.org/dictionary/english/by.

It is possible to argue that these to meanings are to all intents and purposes the same: to express what or who brought something about.

  • What about the function of by here? Nov 24, 2019 at 12:02
  • I was only dealing with the particular usage in the question. There are, of course others, including the Gaelic ‘by here’!
    – Tuffy
    Nov 24, 2019 at 13:42

By used this way is a vestige of the phrase, "by way of". For conciseness, the "way of" part is understood. Via also means, "by way of," and can be substituted for by, but I'd not overuse it.

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