Verbs in their past or present form are called finite verbs (or “tensed verbs”). In any sentence, if there is only one verb, it will be finite, and every sentence needs a finite verb. They can be used for 1st, 2nd, and 3rd person; they are useful as the main verb of the sentence, and they do not rely on any helper words.
Identifying a finite verb
They generally follow their subject.
“Dogs howl at night.”
“Hamsters nap in the daytime.”
Most take an -s when the subject is 3rd person, and the verb is in the present tense.
“Bob dances well.”
“Arnold walks quickly.”
Aside from about 100 irregular verbs, most also use a -d or -ed to indicate past tense.
“Bob danced all evening.”
“Arnold walked to Detroit.”
When forming a question, a finite verb splits to surround the subject.
Bob is dancing; is Bob dancing?
Arnold is walking; is Arnold walking?
As an example, here are the finite forms of one of the most frequently used verb in English, “to be”: is, am, were, was. Notice the tenses.
“Wanda is eating a cheeseburger.”
“I am eating a cheeseburger.”
“They were eating a cheeseburger.”
“My dog was eating a cheeseburger.”