Verbs with “-ing” are either gerunds or participles. Gerunds resemble nouns; participles are more like adjectives.
Adding -ing to a verb gives it the properties of either an adjective or a noun. In the first case, it is known as a participle (of the so-called “present” variety), in the second as a gerund, or “verbal noun”. Other parts of this blog consider each of these -ing uses individually (see 52. Participles Placed Just After their Noun and 70. Gerunds), but here I wish to examine them together in order to offer a clearer idea of their similarities and differences.
Two important similarities between the two kinds of -ing word are their common ability to describe a directly-following noun, and, in other situations, their retention of verb properties like having their own subject/object and being describable by an adverb. The following sections focus separately on each of these.
DIFFERENCES WHEN “-ing” WORDS DESCRIBE A DIRECTLY-FOLLOWING NOUN
Participles describing a directly-following noun are practically the same as adjectives. Examples are a reassuring smile (similar to a friendly smile), falling prices (cp. low prices) and boiling water (cp. hot water). Like adjectives, these -ing forms can be placed after their noun with that is or that are in between, e.g. a smile that is reassuring/friendly, prices that are falling/low (some can even drop that is/are, e.g. the picture emerging – see 52. Participles Placed Just After their Noun).
Gerunds, by contrast, describe a following noun in the same way as ordinary nouns can (see 38. Nouns Used Like Adjectives). Examples are a walking stick, a driving lesson and opening times. One indication that this use is more noun-like is its inability to be paraphrased with that is/are: there is little sense in phrases like *a stick that is walking, *a lesson that is driving, or *times that are opening. Gerunds also pass another test for nouns used like adjectives: we can write them after their noun with a preposition in between: a stick for walking, a lesson about/in driving, times of opening (see 136. Types of Description by Nouns).
With a few -ing words, both the test for a participle and the test for a gerund succeed. For example, a smoking room can become either a room that is smoking (participle) or a room for smoking cigarettes (gerund). This does not mean, however, that the test is invalid; it merely shows that some -ing words can describe a following noun as either a participle or a gerund, the meaning being different in each case.
DIFFERENCES WHEN “-ing” WORDS DO NOT DESCRIBE A DIRECTLY-FOLLOWING NOUN
Participles and gerunds are both more like verbs when they are not describing a following noun, but the fundamental adjective/noun difference is still evident. .
1. Usage at the Start of a Sentence
The difference can be seen in these examples:
(a) Travelling at over 200 km/h, the new trains make a huge difference. (PARTICIPLE)
(b) Travelling at over 200 km/h makes a huge difference. (GERUND)
The word travelling in both sentences is like a verb because it has an adverbial phrase, at over 200 km per hour. At the same time, however, as a participle in (a) it is like an adjective, while as a gerund in (b) it is like a noun.
Travelling is like an adjective in (a) because it has a neighbouring noun (trains) to describe (for more on this adjective characteristic, see 6. Adjectives with no Noun 1: People-Naming and 109. Placing an Adjective after its Noun). This use of a participle before its noun is not the same as the one considered earlier; it allows words to be placed in between, and there must be a comma. More about it can be read in the post 75. How to Avoid “Dangling” Participles. The participle can also come after its noun:
(c) The new trains, travelling at over 200 km/h, make a huge difference.
Commas may or may not be needed in such cases: the rules are the same as for commas with who, which and that (see 34. Relative Pronouns and Commas and 52. Participles Placed Just After their Noun). In (b), on the other hand, there is no neighbouring noun for travelling to describe. This means that travelling, not trains, has to be the subject of the verb makes, so that it is acting like a noun and must be a gerund.
This use of gerunds can look very like the one described earlier. Consider this:
(d) Growing vegetables requires time and money.
How can we tell that the noun vegetables here is the object of growing and not “described” by it? The clue is the singular form of the verb (requires). This prevents the plural vegetables from being the subject, so that growing must be the subject instead, with vegetables its object (giving the meaning “causing vegetables to grow”). If the verb had been require, the subject would have been vegetables, and growing would have had to be a gerund or participle describing it (a participle is actually more likely, because it creates a more logical meaning, “vegetables which are growing”, than the gerund meaning “vegetables for growing”).
Unfortunately, if the noun after the -ing word is singular, the main verb ending cannot help, with the result that a double meaning can occur, like this:
(e) Cooking chocolate is good for you.
It is not clear whether this is about “the cooking of chocolate” (gerund + object) or “chocolate for cooking” (gerund + described noun). It could even mean “chocolate which is cooking” (participle + described noun). For more on structures with multiple possible meanings, see 124. Structures with a Double Meaning.
2. Usage after the Main Verb
Participles and gerunds can go after the main verb in their sentence as well as before it. Participles in this position can still describe a noun placed at the start of the sentence:
(f) The new trains will make a huge difference travelling at over 200 km/h.
Delayed participles like this do more than just describe their earlier noun: they may suggest the idea of “how” (as here) or “and” (see 101. Add-On Participles).
Alternatively, a delayed participle can be a “complement”. Complements are generally adjectives or (pro)nouns that follow BE (or a link verb like it, such as BECOME, REMAIN, LOOK) and describe its subject (see 8. Object-Dropping Errors and 92. Complement-Showing “As”). The adjective-like nature of participles makes it easy for them to be complements:
(g) The increasing frequency of floods is alarming. (PARTICIPLE)
Gerunds can be complements too, corresponding to noun/pronoun ones:
(h) Seeing is believing. (GERUND)
(i) The solution is eating less. (GERUND)
One way of deciding whether an -ing complement is a participle or a gerund is to see if the words the action (or the state) of make sense just before: they should do so only before gerunds. This happens in (i), and also in the following problematic case from the post 69. How Computers Get Grammar Wrong (2):
(j) The key to sounding formal in writing is knowing which words to avoid. (GERUND)
The underlined words resemble the present continuous tense of KNOW, but they are not that because of the normal inability of KNOW to be used in continuous tenses, not to mention the illogical meaning that would be created. The meaning is much more logical if we take is to be the ordinary non-auxiliary use of BE and knowing to be a gerund meaning “the state of knowing”.
Participles and gerunds after a verb are also found in the “object” position. Gerunds can go there by themselves, whereas participles need an accompanying noun or pronoun to describe:
(k) Modern train journeys involve speeding at 200 km/h. (GERUND)
(l) The plan involves TRAINS speeding at 200 km/h. (PARTICIPLE)
A problem with sentences like (k) is that the gerund form is not always the right choice: sometimes the infinitive form (with to) or an ordinary form after that must be used instead. The choice depends on what the main verb is (see 65. Verbs that Mean “Must” or “Can” and 153. Conjunction Uses of “that”). In (l), the noun described by the participle is trains. The extra words at 200 km/h force the participle to follow this noun; without them it would go before.
The following exercise may help the points about pre-noun -ing words to be better understood and remembered. You have to decide whether each -ing word is a gerund or a participle (answers below).
1. a walking stick
2. thinking time
3. a defining moment
4. a compelling reason
5. meeting rooms
6. taxing work
7. an opening ceremony
8. pressing matters
9. a sticking point
10. a living wage
11. a helping hand
12. passing ability
1. GERUND: a stick for walking; 2. GERUND: time for thinking; 3. PARTICIPLE: a moment that defines; 4. PARTICIPLE: a reason that compels … (…action to be taken); 5. GERUND: rooms for holding meetings; 6. PARTICIPLE: work that taxes (= demands energy); 7. PARTICIPLE: a ceremony that opens; 8. PARTICIPLE: matters that press (for attention); 9. GERUND: a point where things may get stuck; 10. GERUND: a wage for staying alive; 11. PARTICIPLE: a hand that helps; 12. GERUND: ability in passing (a ball to another player)