In English, the ing form, for example swimming or smoking, is both a noun and a verb. You can follow it by an object, smoking cigarettes, by a verb, swimming is good, or you can make it the object of a sentence, I like swimming.
After verbs
You use the ing form after some verbs such as enjoy, admit, appreciate, can't stand / help / bear, deny, avoid, mind, understand.
For example, "I can't stand doing nothing", or "she denied breaking the copier".
With 'from' and 'to' with some verbs
Prevent / stop someone from doing: "He prevented her from leaving."
Look forward to doing: "We look forward to hearing from you soon."
Object to doing: "Does anyone object to me smoking?"
Get used to doing: "It took him a long time to get used to living in a city."
Prefer something to doing something else: "I prefer cooking to doing the dishes."
After prepositions
"Before going out he turned off the heating."
"I'm tired of arguing."
"These are used for cracking walnuts."
"I passed the exam by remembering the equations."
In some fixed expressions
"As well as doing…"
"It's no good doing…"
"It's no use doing…"
Some verbs can use either the 'to do' or the 'ing' form
See / hear / watch someone do / doing
With the verb form do, you see or hear the whole action. For example,"I heard him tell you about the letter."
With the verb form ing you only see or hear part of the action. For example, "I saw her drinking a coffee in the bar."
Remember / regret
If you use ing after these verbs, you are talking about something that happened before. "I remember coming here as a child" – I'm not a child any more, but I remember the times when I came here before.
"I regret not studying." (I didn't study in the past and I regret it now.)
If you use the to do form after these verbs, then you are referring to something in the future.
"Please remember to turn off the lights." (Please don't forget to do it later.)
"I regret to inform you that…" (I'm just about to tell you some bad news.)
Stop
"I want to stop smoking." (I want to break my habit.)
"She stopped to sit down." (She stopped walking so that she could sit down.)
Try
Try + ing = try out this experiment.
Try reading something in English every day." (You may be surprised at the results!)
Try to do = try hard to do something.
"Please try to be quiet when you come in." (Please make an effort.)