keep
used as a transitive verb
If you keep something or someone in a place, you cause them to remain in that place. The past tense and -ed participle of keep is kept.
Where do you keep your keys?
The doctors kept her in hospital for another week.
To keep someone or something in a particular state means to cause them to remain in that state.
The fire kept them warm.
They had been kept awake by birds.
used as an intransitive verb
To keep in a particular state means to remain in that state.
They've got to hunt for food to keep alive.
used with an -ing form
Keep can be used in two different ways with an -ing form.
You can use it to say that something is repeated many times.
The phone keeps ringing.
My mother keeps asking questions.
You can also use it to say that something continues to happen and does not stop.
I turned back after a while, but he kept walking.
The fire is still burning. I think it'll keep going all night.
For emphasis, you can use keep on instead of ‘keep’.
Did he give up or keep on trying?
Be careful
Don't say that someone or something ‘keeps to do’ something.
Don't say that someone or something ‘keeps to do’ something.