こと

こと

"こと" refers to "thing," "matter," or "event" (abstract or intangible).

Here, the particle 'こと' nominalizes the verb '弾く' so that it can function as a noun (playing).

ピアノを弾くことが好きです。

I like playing the piano.

In this sentence, 'こと' is used to refer to the occurrence or fact of raining, serving as a conceptual marker for the action.

雨が降ることを知らなかった。

I didn't know that it would rain.

Here, 'こと' refers to matters or things related to '旅行' (trip), emphasizing the concept of the event or situation.

旅行のことを考えています。

I am thinking about the trip.