International calling codes are numerical prefixes used to dial telephone numbers in different countries. Each country is assigned a unique code, which typically starts with a "+" sign followed by one to three digits. For example, the code for the United States is +1, while India has the code +91. These codes help route calls across international borders. When making an international call, you must first dial your country's exit code, followed by the international calling code of the destination country, and then the local phone number. This system ensures that calls are correctly directed to the intended recipient, regardless of their location.