A gerund is a verb form ending in -ing that functions as a noun.
An infinitive is the base form of a verb, usually preceded by “to” (to run, to eat), that can act like a noun, adjective, or adverb.

Gerunds (verb + -ing) and infinitives (to + verb) both act like nouns but have different uses and meanings.

Below is a concise, teachable breakdown with rules, common verbs, contrasts, and examples.

1. Basic forms

Gerund: verb + -ing

swimming, eating, reading.

Infinitive (full/“to” infinitive): to + verb

to swim, to eat, to read.

Bare infinitive: base verb without to (used after modal verbs, let/make/certain expressions)

can swim, let him go.

2. When to use gerunds (main uses)

• As subjects:

  Swimming is good exercise.

• After certain verbs (enjoy, avoid, mind, suggest, finish, admit, deny, consider):

  I enjoy reading.
  She admitted taking the book.

• After prepositions (including phrasal verbs and prepositional verbs):

  I’m good at drawing.
  He left without saying goodbye.

• As objects of possessive + gerund (showing who performed the action):

  I appreciated her helping me.

• After certain adjectives + preposition:

  She’s interested in learning Spanish.

3. When to use infinitives (main uses)

• To express purpose:

  I went to the store to buy milk.

• After certain verbs (decide, plan, hope, want, promise, refuse, learn, need, expect):

  They decided to leave.
  I hope to see you soon.

• After adjectives:

  It’s easy to learn.
  She’s happy to help.

• After certain nouns (a chance to win, a decision to leave):

  He gave me a chance to speak.

• After question word + to (ask what to do):

  I don’t know what to say.