The -ing form of the English verb is used to make continuous tenses:

I study English simple present
I am studying English present continuous

Tom lived in Rome simple past
Tom was living in Rome past continuous

We will work here simple future
We will be working here future continuous

But an -ing form can also be a noun and behave like a noun. In this case, it can go with or without an object.

SUBJECT
noun English is easy
-ing Loving is easy   /   Loving you is easy

OBJECT
noun I like books
-ing I like reading   /   I like reading books

COMPLEMENT
noun My favourite activity is tennis
-ing My favourite activity is reading    /   My favourite activity is reading books

PREPOSITIONAL COMPLEMENT
noun Thank you for the present
-ing Thank you for waiting    /    Thank you for helping me

WITH POSSESSIVE ADJECTIVES
noun I like your eyes
-ing I like your dancing    /    I like your looking at me

VERB AFTER PREPOSITIONS AND CONJUNCTIONS (connectors)
Remember this important rule: After prepositions and conjunctions we use the ing-form of the verb:

after preposition Thank you for waiting / He's thinking of going on holiday
after a conjunction We had to walk because driving there was impossible.