Infinitive is prefaced with the word “to”
For examples:
– To think
– To act
– To walk
– To talk
– To write
– To listen

Both infinitives and gerunds can act as the subject of the sentence:
– To think is something that comes naturally (infinitive)
– Thinking is something that comes naturally (gerund)

You can use infinitive or gerund as the object of a verb:
– I like to fish (Infinitive)
– I like fishing (Gerund)

Only gerund can be the object of a preposition. An infinitive cannot:
We are thinking about walking in the woods

Gerund is a noun formed from a verb. A gerund always contain the ending “-ing.”
Functions of Gerund:
1) Gerund as Subject
For examples:
– Reading novel is my hobby
– Being a good doctor is my ambition

2) Gerund which is used with these verb as follows:
– Deny
– Avoid
– Suggest
– Consider
– Admit
– Enjoy
– Miss
– Consider

For examples:
– He always denies helping me
– Why do you always avoid meeting her?

3) Gerund which is used after preposition, it can stand before verb, adjective, or noun.
For examples:
– You should give up smoking
– I am thinking of going to Bali with you

4) Gerund can be used for complement
For example:
– Their favourite activity is playing music

5) Gerund can be used to explain noun modifiers
For example:
– You can wait for me in the waiting room

6) Gerund can be used in this form of sentence “It………ing.”
For examples:
– It is nice talking with you
– It is no use trying to meet her

Reference:

Tumijo and Riyanto Slamet (2010) Metode Terbaik Melejitkan Skor TOEFL, Penerbit Pustaka Widyatama: Yogyakarta.