A book by the A verb is customarily defined as a part of speech (or word class) that describes an action or occurrence or indicates a state of being. But just when is a word a verb?

Generally, it makes more sense to define a verb by what it does than by what it is. Just as the 'same' word (rain or snow, for example) can serve as either a noun or a verb, the same verb can play various roles depending on how it's used.

Put simply, verbs move our sentences along in many different ways.

Here, by identifying 10 types of verbs, we'll briefly consider some of their more common functions.

Auxiliary Verbs and Lexical Verbs

An auxiliary verb (also known as a helping verb) determines the mood or tense of another verb in a phrase. In the sentence 'It will rain tonight,' for example, the verb will 'helps' the verb rain by pointing to the future. The primary auxiliaries are the various forms of be, have, and do. The modal auxiliaries include can, could, may, must, should, will, and would.

A lexical verb (also known as a full or main verb) is any verb in English that isn't an auxiliary verb: it conveys a real meaning and doesn't depend on another verb: 'It rained all night.'

Dynamic Verbs and Stative Verbs

A dynamic verb indicates an action, process, or sensation: 'I bought a new guitar.'

A stative verb (such as be, have, know, like, own, and seem) describes a state, situation, or condition: 'Now I own a Gibson Explorer.'

Finite Verbs and Nonfinite Verbs

A finite verb expresses tense and can occur on its own in a main clause: 'She walked to school.'

A nonfinite verb (an infinitive or participle) doesn't show a distinction in tense and can occur on its own only in a dependent phrase or clause: 'While walking to school, she spotted a bluejay.'

Regular Verbs and Irregular Verbs

A regular verb (also known as a weak verb) forms its past tense and past participle by adding -d or -ed (or in some cases -t) to the base form: 'We finished the project.'

An irregular verb (also known as a strong verb) doesn't form the past tense by adding -d or -ed: 'Gus ate the wrapper on his candy bar.'

Transitive Verbs and Intransitive Verbs

A transitive verb is followed by a direct object: 'She sells seashells.'

An intransitive verb doesn't take a direct object: 'She sat there quietly.' (This distinction is especially tricky because many verbs have both transitive and intransitive functions.)

Does that cover everything verbs can do? Far from it. Causative verbs, for example, show that some person or thing helps to make something happen. Catenative verbs join with other verbs to form a chain or series. Copular verbs link the subject of a sentence to its complement.

Then there are performative verbs, mental-state verbs, prepositional verbs, iteratives, and reporting verbs. And we haven't even touched on the passive or the subjunctive.

But you get the idea. Though they can get tense and moody, verbs are hard-working parts of speech, and we can count on them to make things happen in many different ways.

* Stephen Pinker, The Stuff of Thought. Viking, 2007​

The verb 'to be' is one of the shortest and most important—yet oddest—verbs in the English language. It is an irregular verb; indeed, it is the only verb in English that completely changes form in every tense. The verb 'to be' is probably the most important verb in English. It can be used in simple statements such as:

• How are you?
• It is a beautiful day!
• I am from Italy.

The 'to be' verb can also be used to express complex thoughts: It is the verb at the very core of one of William Shakespeare's most famous plays, Hamlet, where the title character speaks the famous line: 'To be, or not to be.' ('Hamlet,' Act 3, Scene 1) Hamlet was asking whether it is better to be dead or alive, or in other words, whether to exist or not exist.

At heart, that's what the 'to be' verb connotes: a state of being or existence. It's a very common verb, but it's important to learn how to use it properly.

'To Be' as a Linking, Transitive, or Auxiliary Verb

Before conjugating the verb 'to be' in the present and past forms, it's important to understand what this verb does. The verb 'to be' is is a stative verb: It refers to the way things are—their appearance, state of being, and even their smell. 'To be' or 'be' can be a linking verb: It joins the subject of a sentence to a word or phrase that tells something about the subject, such as in these examples:

• Jennifer is my sister.
• That television show is interesting.
• Our house is in the countryside.

'To be' can also be an auxiliary—or helping—verb: It works with the main verb, as in these examples:

• Kim is making a clay vase.
• Joe had built his first model rocket last year.
• People have admired Michelangelo's sculptures for centuries.

'To be' can also be a transitive verb, which is a verb that takes an object, either a direct or an indirect object. An example would be: 'Sue is talking.' In the sentence, the 'to be' verb, 'is,' takes a direct object, 'talking.'

Present Tense

The present tense of the verb to be, as with any verb, can take several forms: the indicative or simple present, present perfect, and present continuous.

The tables below show how to conjugate to be in these forms:

Note that even in the indicative—or simple—present tense, the verb changes in the first, second, and third person uses.

Present Perfect

The present perfect, formed by combining has or have with a past participle, usually a verb ending in -d, -ed, or -n, indicates actions or events that have been completed or have happened in the present.

Examples of the present perfect include:

• I have been a teacher for many years.
• She has been to France more than 10 times in her life.

To correctly use the verb in the present perfect, just remember that only the third-person singular uses 'has.' All of the other forms in this tense use 'have.'

Present Continuous

The present continuous, also known as the present progressive, is generally used to express something happening at the moment.

An example sentence might be: 'That course is being taken by a number of students.' Notice how the 'to be' verb changes depending on the person—first, second, or third—as well as the number, singular or plural.

There's no easy trick to learning which form of 'to be' to use here. Just remember, the first person, singular requires 'am,' second person requires 'are,' and 'third-person singular requires 'is.' Fortunately, all the plural forms use 'are.'

Past Simple

Past simple indicates that something happened at some specific time in the past, such as: 'Her house was built in 1987.'

Note that the past singular requires 'was' for the first and third person, while 'were' is used with a second-person pronoun. All forms are the same—'were'—for the plural tenses.

Past Perfect

The past perfectindicates actions or events that have been completed or have happened in the past.

Some examples include:

• Peter had been to the office before they arrived.
• How long had you been in town before he called you?

Peter had been to the post office presumably only once before they arrived, and the person being addressed in the second sentence had 'been in town' for a specific time period before 'he called.'

Past Continuous

The past continuous is usually used to refer to events happening at the same time that something important was occurring.

An example of the past continuous in a sentence would be: 'The ideas were being discussed while the decisions were being made.' In this case, the past continuous is used twice to highlight how one action was taking place at the same time as another: Ideas 'were being' discussed at the same time decisions 'were being' made.

Other Present and Past Uses

'To be' can also be used in other ways in the present and past tense, such as:

• The comparative or superlative form to make a comparison between people, places, objects, and ideas. Used as such, the 'to be' verb works like an adjective: 'The Mercedes is faster than the Fiat,' or 'The Mercedes is the fastest car on the lot.'
• In the modal form, also known as the present possibility, indicating that something may occur, as in: 'He should be at church waiting for us,' and past possibility indicating that something might have happened in the past, as in: 'He might have been at school or at home.'

• A copular verb where 'to be' joins the subject of a sentence or clause to a complement. These complements are generally descriptions that are often adjective or noun phrases, such as 'I am sometimes late for work.'

A copular 'to be' verb is essentially a transitive verb, except that the object is a phrase or clause rather than a single word. In this case, the 'to be' verb, am, links the subject 'I' with the description of the subject, (a person who is) 'sometimes late for work.'