Grammar Point
noun (common) (futsuumeishi)
n 
word usually written using kana alone
uk 
こと

thing, matter

Verb (Informal) + こと

こと is used as a nominalizer to refer to intangible things, matters, or facts, as opposed to physical objects. It is often used to turn a verb or an entire clause into a noun phrase.

When added to the informal form of a verb, it transforms the action into a noun phrase representing the 'act' or 'matter' of doing that verb.

I like reading books.

The important thing is to try.

Note

こと is specifically for intangible concepts like ideas, actions, or experiences. For physical, tangible objects, the word 'もの' should be used instead.

Adjective + こと

こと can be used with adjectives to describe an intangible quality or a matter that possesses a certain characteristic.

い-Adjective + こと

い-Adjectives directly precede こと.

I forgot a happy thing.

な-Adjective + な + こと

な-Adjectives require the particle な before こと.

I am thinking about a strange thing.

Noun + の + こと

こと can follow a noun to refer to matters or facts concerning that noun.

The particle の is used to link a noun to こと to indicate 'matters concerning' that noun.

I am thinking about my family.

I know about Japan.

Note

This construction is very common when expressing feelings or thoughts about a person or a specific topic, meaning 'the matter of' or 'about'.

Words: 
事こと
事こん
縡こと
縡こん
Radicals of radicals