1. Present Participle: This is the most common use of "-ing". It forms the present participle of a verb, which can be used in several ways:
* As part of a continuous verb tense: "I am singing."
* As an adjective: "The singing bird."
* As a noun: "The singing was beautiful."
2. Gerund: A gerund is a verb form ending in "-ing" that functions as a noun.
* "Swimming is good exercise." (Here, "swimming" is the subject of the sentence.)
* "I enjoy hiking in the mountains." (Here, "hiking" is the object of the verb "enjoy".)
3. Adjective: Sometimes "-ing" is added to a noun to form an adjective describing the noun.
* "The waiting room."
* "The dining table."
4. Noun: Some words ending in "-ing" are simply nouns.
* morning
* evening
* feeling
It's important to note that the meaning of "-ing" can change depending on the specific word and its context in a sentence.