The first type of verbs, "transitive", or "action" verbs describe something that actually happens... there's usually motion involved: to run, to jump, to laugh, to cry.

The zombies chased me.

Transitive verbs often take an object (a noun or phrase that completes the verb by answering the questions who? or what?). If we just wrote, The zombies chased, someone would expect to know who or what they were chasing.

"Intransitive" verbs are different —nothing happens! Instead, these verbs express a state of being. All of the following examples use intransitive verbs.

The zombies are ugly.

Unicorns exist.

My parents waited.

The walrus slept.

No one who reads or hears those sentences expects an extra word to complete the thought. No one wonders, "Unicorns exist what?"

Some verbs can be transitive or intransitive, depending on how they are used in the sentence.

The zombies smell brains.

Unicorns smell.

In the first sentence smell is transitive, and needs an object (What do the zombies smell? Brains!) In the second sentence, we're just stating a fact: unicorns have a particular odor. We're not saying it's good or bad, just that it exists.

Helping verbs never appear on their own as the main verb in a sentence. They always need another verb to complete them. There are not many of them, but they are among the most common words in the language. Helping verbs are used to express the tense, aspect, mood or voice of the main verb. Helping verbs can be further subdivided into auxiliary verbs and modal verbs.

These are the three most important verbs in English! They are also weird, because they're irregular.

To be

"To be" has the separate forms am, are, is in the present and was, were in the past. The past participle is been.

These forms of "be" are used with the past participle to form the passive voice, and with the present participle (the -ing form) to make the progressive/ continuous tenses.

Karen is eating a sandwich.

We were living a lie.

My team was defeated in the championship game.

The children were given candy.

Forms of "to be" can also be used on their own —without a main verb— as linking verbs, which means they just show a connection between the subject and a noun or adjective.

Karen is a monster.

That was funny.

To have

"To have" has the forms have and has in the present and had in the past. The past participle is also had.

These forms are used with the past participle to indicate the "perfect" aspect of a verb (i.e. to form the past/present/future perfect and perfect progressive tenses.)

We have eaten breakfast already.

The criminal has escaped from jail.

The cold weather will have killed all the mosquitoes.

Note that to form the perfect progessive tenses you need a "to be" verb and a "to have" verb. Perfect tenses require a form of "to have" and a past participle, while progressive tenses require a "to be" verb and the present participle. In these tenses we use the past participle of "to be", been, together with the correct form of "to have".

The dogs had been eating for fifteen minutes.

My enemies have been laughing at me all day.

By the time Sam arrives the teacher will have been talking for an hour.

Also note that the verb "have" can also be used as a regular (intranstive) verb to show ownership.

I have a million dollars in the bank.

When used in this way it can be the main verb in complex tenses.

The Johnsons were having a picnic.

The movie star had had three previous wives.

In the last example, the first had shows "past", and the second had is the past participle, so together they form the past perfect of "to have".

To do

"To do" has the forms do, does in the present and did in the past. The past participle is done. "To do" is often used as a main verb:

Bob did his taxes.

It can also be used as an auxiliary verb to form questions

Do you like tacos?

Or to make the negative form of a verb

I do not like tacos.

Or to add emphasis

But I do like pizza.

Modal verbs are used to show how or in what manner something is done, to show possibility, or to form conditionals and requests.

Birds can fly.

Nobody could explain how to solve the problem.

No one dared eat the extra spicy noodles.

The neighbors may learn my secret.

The Professor might know the answer.

You must stop sneaking up on me!

We need not water the garden because it rained.

You ought to eat that cookie.

The meek shall inherit the earth.

We should see that new movie.

Everybody will know I cheated.

If I was a king I would eat chocolate every day.

Modal verbs are a complicated subject, and if you are not exactly sure how to use one, you should check the dictionary. ACTD!

Phrasal verbs are verbs that are made up of more than one word. The second word is usually a prepositon, but in a phrasal verb it does not function (always) as a preposition. Phrasal verbs have to be learned as vocabulary, because their meaning is often different than what one would expect from a combination of the root verb and the preposition.

The writer tore up the first draft of his article.

In this case, the preposition up no longer functions as a preposition, as it doesn't have an object like a preposition should. The sentence does have an object, the phrase "the first half of his article", but it is the object of the verb "tore up", not of a preposition "up". Also, the meaning of "tear up" is not obvious from "tear" and "up".

Do you want to hang out?

Here, "out" no longer functions as a preposition (it doesn't have an object.)

Phrasal verbs can also be made up of more than two words.

Why do you put up with his attitude?

Phrasal verbs are not obvious. Sometimes, a verb and a preposition can go together in the same order, but in one sentence they form a phrasal verb, but in another the preposition is part of a normal prepositional phrase that just happens to follow the verb.

Alice looked up Ed's phone number.

We looked up the mountain.

The first example uses the phrasal verb look up, in the second up starts a prepositonal phrase that functions as an adverb (it tells where we looked.) If you are not sure if a verb + preposition combination is a phrasal verb, you should check the dictionary.  ACTD!

Sometimes, verbs can act like nouns in a sentence. This normally happens with the infinitive or past or present participles.

Infinitives as nouns

To live is to love.

The object of the game is to win.

An infinitive acting like a noun can be modified by adverbs or prepositional phrases just like any other verb. (Such a group of words is called an "infinitive phrase".)

To win at chess takes skill.

Owls like to sleep regularly.

Past participles as nouns

Sometimes people will use a past participle as a noun. When this happens, it generally refers to some group with that characteristic, but the actual word for the group has been omitted.

The dead have risen from their graves!

My beloved is meeting me at sunset.

In these cases, the past participle is being used as an adjective, but the noun it's modifying must be understood from context. One must simply understand that my beloved means my beloved person.

Two more details to note about this usage: the past participle is treated as a singular, specific noun, so it is used with the article "the"; and it can be modified with an adjective i.e. the grateful dead or an adverb the recently dead.

Present participles as nouns (gerunds)

It is very common to use the -ing form of a verb as a noun to refer to the act itself.

Swimming is great exercise.

Laughing during funerals is considered rude.

I love cooking.

Gerunds (present participles acting like nouns) can be modified by adjectives like nouns the wild dancing .