-ing

-ing is a suffix used to make one of the inflected forms of English verbs. This verb form is used as a present participle, as a gerund, and sometimes as an independent noun or adjective. The suffix is also found in certain words like morning and ceiling, and in names such as Browning.

The Modern English -ing ending, which is used to form both gerunds and present participles of verbs (i.e. in noun and adjective uses), derives from two different historical suffixes.

The gerund (noun) use comes from Middle English -ing, which is from Old English -ing, -ung (suffixes forming nouns from verbs). These in turn are from Proto-Germanic *-inga-, *-unga-, *-ingō, *-ungō, which Vittore Pisani [it] derives from Proto-Indo-European *-enkw-. This use of English -ing is thus cognate with the -ing suffix of Dutch, West Frisian, and the North Germanic languages, and with German -ung.

The -ing of Modern English in its participial (adjectival) use comes from Middle English -inge, -ynge, supplanting the earlier -inde, -ende, -and, from the Old English present participle ending -ende. This is from Proto-Germanic *-andz, from the Proto-Indo-European *-nt-, and is cognate with Dutch and German -end, Swedish -ande, -ende, Latin -ans, -ant-, Ancient Greek -ον (-on), and Sanskrit -ant. -inde, -ende, -and later assimilated with the noun and gerund suffix -ing. Its remnants, however, are still retained in a few verb-derived words such as friend, fiend, and bond (in the sense of "peasant, vassal").

The standard pronunciation in modern English is /ɪŋ/, with a velar nasal consonant. Variants include /ɪŋg/ (e.g. Northern England), /ɪn/ or /ən/ (widespread) and /i(ː)n/ (mainly US, but also in Canada).

The variants with /n/ may be denoted in writing with an apostrophe: runnin' for running. Sometimes known as g-dropping, the use of variants such as these is one of the most frequently studied sociolinguistic variables in English. The /n/ variants are believed to descend directly from the aforementioned Old English participle suffix -ende.

All English verbs (except for modals and other defective verbs that do not have gerunds or participles) make the inflected form in ‑ing regularly. Thus go makes going, read makes reading, fail makes failing, and so on. In certain cases there are spelling changes, such as doubling of consonants (as in sit → sitting) or omission of mute e (as in change → changing). It does not apply in the case of monosyllabic words in English that are omitting the mute e (as in age becoming ageing, though aging is also found). For details of these rules, see English verbs.

The -ing form of a verb has both noun uses and adjectival (or adverbial) uses. In either case it may function as a non-finite verb (for example, by taking direct objects), or as a pure noun or adjective. When it behaves as a non-finite verb, it is called a gerund in the noun case, and a present participle in the adjectival or adverbial case. Uses as pure noun or adjective may be called deverbal uses.