Let's start from the basics

Gerund (Present Participle):

VERB + -ING (eating, going, studying)
Infinitive: TO + BASE VERB (to eat, to go, to study)

Both gerunds and infinitives are action words (i.e., verbs) in meaning, but they act like nouns in the sentence.


They always take a noun position: a subject or an object of the main verb.
A gerund or infinitive is never the main verb.
Incorrect:

• I to study
  
• I studying
  
  

Correct:
• Studying is fun.
• I need to study.


Three Gerund Rules

1. Gerund = Subject
• Reading is my favorite time of the evening.

2. Preposition + Gerund
• I thought about calling my grandma, but I was too tired.

3. Verb + Gerund
• They enjoy making crafts in class.


*Don't forget that some verbs take either a gerund or an infinitive with no change in meaning! Some common verbs include like, love, and hate.


• She likes watching movies.
• She likes to watch movies.


Three Infinitive Rules

1. Adjective + Infinitive
It is fun to play video games on the weekend.

2. Noun + Infinitive
• Did you want me to call you?

*Note: This rule is very helpful, because it is stronger than the "verb + gerund"

3. Verb + Infinitive
• He wants to learn Japanese.


Tip: Using a gerund suggests that you are referring to real activities or experiences.

Using an infinitive suggests that you are talking about potential or possible activities or experiences.

So let's say you eat ice cream every day. This is an actual action you are doing. Then you could say: "I like eating ice cream".
On the other hand, if you are on a diet, and you don't usually eat ice cream, then you are talking about a potential action. You could say: "I like to eat ice cream."


Some verbs are only followed by a gerund.
For example:
Anticipate, appreciate, keep, miss, risk, suggest, etc.

Some verbs take only an infinitive.
For example:
Agree, choose, get, hope, learn, manage, wait, want, wish, etc.

Some verbs can be followed both by gerunds and infinitives, with only a slight difference in the meaning.
For example:
I like eating ice cream/ I like to eat ice cream.

A few verbs take both gerunds and infinitives, but with a significant difference in the meaning.
For example:
Forget, regret, stop, remember, try.

She regrets quitting her job.(She quit her job, and now she regrets it.)
She regrets to quit her job.(She is sorry to quit her job. She didn't do it yet)