A collective pronoun is a pronoun that refers to a group of people or things. The two most common collective pronouns are 'our' and 'they'. 'Our' is a first-person plural pronoun, meaning it is used to refer to a group that includes the speaker. 'They' is a third-person plural pronoun, meaning it is used to refer to a group that does not include the speaker. Both of these pronouns can be used to refer to a group of people, animals, or things.