1. used to refer to two or more people or things previously mentioned or easily identified
Usage: third person plural
2. used to refer to a person of unspecified gender
Usage: singular use
3. used to refer to people in general
Usage: indefinite use

Examples

• The students finished their homework, and they went home.
• Where are my keys? They were on the table.
• Someone left their umbrella here, but they haven’t come back for it.
• If a customer complains, they should speak to the manager.
• They say it’s going to rain tomorrow.
• They built this bridge in 1950.
• The books are heavy, so they need to be carried carefully.