Like the determiners, pronouns are short and relatively few. The personal pronouns are I, you, he, she, it, we, they. That is the form they take when they are the subject of a clause, that is, when they initiate whatever meaning is described in the verb. When they are on the receiving end of the verb, and form the object of a clause, or when they are the complement of a preposition, they take the forms me, you, him, her, it, us, them.
Personal pronouns are among the few reminders that English was once a fully inflected language, that is, one in which the role of the words in a sentence was shown by their endings rather than by the order in which they were placed. In Standard English today we still have to say I hit the ball and not *Me hit the ball and we have to say The ball hit me and not *The ball hit I. It would still be possible to extract the sense if we changed the word order in the second and third of those sentences. Though both ungrammatical in normal prose *Hit I the ball still tells who does the hitting and *The ball me hit still tells us who was hit.
Related to the personal pronouns are the possessive determiners my, your, his, her, its, our and their. In English, the gender of the third person singular possessive determiner is normally determined by the sex of the person it refers to. His house tell us that the owner is male, her house tells us that the owner is female. In French, by contrast, the gender is determined by the grammatical gender of the following noun. In French, it’s always sa maison, regardless of whose maison it is because maison is grammatically feminine. French thus avoids a problem which gives much anxiety to some English speakers. Take the sentence Until the water level has gone down, no-one must leave his house. His? Doesn’t the instruction apply to women as well then? Well, yes, it does. How do we express the fact? English doesn’t have a gender neutral third person singular possessive determiner, does it? Oh, but it does. We can say, and many people do say, Until the water level has gone down, no-one must leave their house. Their and the other forms they, them, their and themselves do double duty. They can be used with both singular and plural referents.
Possessive determiners are not pronouns in themselves, unlike mine, your, his, hers, ours and theirs which are possessive pronouns. They replace nouns in clauses like This is mine and That is yours. There is no possessive pronoun its, because we never need to use it. We don’t say, for example, of a house *This door is its in the way that we might say This house is mine.
Finally among the forms of the personal pronouns are the reflexives: myself, yourself, himself, herself, itself, ourselves, yourselves and themselves. These are used to reflect the action of the verb back onto the subject, as in They washed themselves. They are also used for emphasis, as in I did it myself, meaning that I and no one else did it. There is also a tendency for the reflexive pronouns to replace personal pronouns in some contexts. We might hear, for example, They’ve invited John and myself instead of They’ve invited John and me.
There is no space in this post to discuss the use of all the other pronouns in English, but they include:
the demonstrative pronouns: this, that, these, those
the indefinite pronouns such as everybody, something, anyone, anything, nothing.
the quantifying pronouns: some, both, each, either, neither, all, many, enough, any, much, several, none, little, few
the relative pronouns: who, whom, which, whose, that (although, it has to be said, not all grammarians regard that as a relative pronoun)