Have and has are different forms of the verb to have. Even though they come from the same word, there are slight differences in the way they’re used. Have is used with I, you, we, and they, while has is used with he, she, and it. The verb to have has many different meanings. Its primary meaning is to possess, own, hold for use, or contain.
Have is the conjugation of to have that’s used when speaking in the first person (I, we), the second person (you), or the third person plural (they). Take, for example, the following sentence: “They have two dogs.” Here, have is the correct choice because the subject (they) is a third person plural pronoun.
Has is the conjugation of to have that’s used when speaking in the third person singular (he, she, and it). Bear in mind, this only really applies when you’re speaking in the present tense (describing events that are currently happening). This example from And the Mountains Echoed by Khaled Hosseini shows has used with a third person singular pronoun (he): “He has a slender nose, a narrow mouth, and tight blond curls.”
The Present Perfect Tense
Have or has can be used with the past participle form of another verb to create the present perfect tense. The present perfect tense is used to communicate that the action of the verb was completed prior to the present. In the sentence “She has lived here for four years,” for example, has is an auxiliary verb (a helping verb used in the construction of verb forms), and lived is the past participle. Together, they form the present perfect tense.
Another example of the present perfect tense is seen in this sentence from The Night Circus by Erin Morgenstern: “‘I have invited you all here for a reason,’ Chandresh says, ‘as I’m sure you have surmised by now.'” In the first part of the sentence, have is used because there is a first person subject (I). In the second part of the sentence, have is used again because there is a second person subject (you).