A telephone number is a unique series of digits assigned to a telephone line, allowing individuals to make and receive calls. Typically, a telephone number consists of an area code, which identifies a specific geographic region, followed by a local number that connects to a particular phone. Telephone numbers can vary in length depending on the country. In many places, they are formatted with parentheses and dashes for easier reading, such as 555-123-4567. Modern technology also allows for mobile phones to have their own unique numbers, enabling communication across different devices and networks.