A verb is a word that expresses an action, describes an occurrence, or establishes a state of being. Every sentence needs at least one verb, which is paired with the subject. All verbs have tense, aspect, and mood, of which there is a wide variety of combinations. These concepts are part of the foundation of accurately expressing your thoughts in writing.

Verb Tense 

Tense indicates when the action expressed by a verb takes place. The three simple tenses are past, present, and future.

Different tenses take different verb forms, either by changing the word itself or by adding helping verbs. There is no single formula for how to change verb tenses. Here are a few examples:

Present Tense

Present tense expresses unchanging actions and states of being. It is also used with recurring actions and with universal or widespread truths.

• I walk
• She runs

Past Tense

Past tense is used for actions that started and finished in the past.

• I walked
• She ran

Future Tense

Future tense expresses an action or event that will take place in the future.

• I will walk
• She will run

Verbal Aspect

"Verbal aspect" refers to the timing of the verb. More specifically, it addresses whether the action occurs in a single block of time, continuously, or repetitively. All verbs have both tense and aspect. Verbal aspect consists of simple, progressive, perfect, or perfect progressive, where each refers to a different fabric of time. 

Simple

The simple aspect is used to express a single action, a repeated action, or a permanent state. 

• Permanent state: David lives in Raleigh, North Carolina. 
• Repeated or habitual action: He runs every morning. 
• Single action: He graduated from the University of North Carolina. 

Progressive

The progressive aspect is used to talk about continuous events.

• Dr. Jones was lecturing about grammar. 
• Jane is reading a novel. 

Perfect 

The perfect aspect is used to discuss completed actions. It is often formed by the verb have combined with a past tense verb. 

• My family had left before the flooding reached our home. 
• She has visited their mountain home. 

Perfect Progressive

The perfect progressive combines the perfect and the progressive to refer to the completed portion of a continuous action. 

• The news crew had been working for more than twelve hours to provide full coverage of the event. 
• I will have been sleeping for many hours by then.

Verbal Mood

Verb mood is to the "attitude" of the verb. More specifically, "mood" refers to the degree of necessity, obligation, or probability. Is it a statement of fact? Is it a command? Mood can be expressed in any verb tense. The three main moods used in English are indicative, subjunctive, imperative. 

Indicative

The indicative mood is used for factual statements.

• Sally is drinking coffee.
• Sally drinks coffee.
• Sally drank coffee. 

Subjunctive

The subjunctive mood is for hypothetical situations, emotions, or making requests. It is often (but not always) paired with a clause containing would, should, or could, or an if-then statement.

• If I were a pilot, I would fly through the clouds.
• The carousel closed. I wish it were still in use. 

Imperative

The imperative mood is used to give commands. 

• Go finish your homework. 
• Please hang your coat. 
• Don't eat a snack now or  you'll ruin your supper. 

Special Types of Verbs

Linking Verbs

Linking verbs are used to connect subjects with their complements. They may be the main verb in a sentence, even if they express a description rather than an action. The most common linking verb is to be, which takes many different forms:

• This tea is hot.
• There are many books in his library.

Other common linking verbs include the following:

• appear
• become
• seem
• taste
• continue
• remain

Linking verbs take no direct objects. Consequently, if a sentence's main verb is a linking verb, it cannot be written in the passive voice.

Transitive Verbs

Transitive verbs describe actions that are done to a specific thing, called the verb's direct object.

• She cut her hair. (Subject: She. Transitive verb: cut. Direct object: her hair.)
• Romeo kissed Juliet. (Subject: Romeo. Verb: kissed. Object: Juliet.)

All of the verbs are performed by the subject, to something or someone else.

Intransitive Verbs

Intransitive verbs are actions that are complete on their own, and do not require any object:

• Sally ran fast.
• The bird flew.

Most verbs can be classified as transitive or intransitive, depending on their context. Just remember, if your verb has an object, make sure it's clear to the reader: Don't say "Sally kissed her" if you don't know who "her" is! 

He walked the wire

The verb tense in the title signals that this action took place in the past. It is not only important to have subject and verb agreement, but also to utilize the correct verb tense to ensure that a sentence contains its intended meaning.