A tax identification number (TIN) is a unique identifier assigned to individuals and businesses for tax purposes. It helps the government track tax obligations and ensure compliance with tax laws. In the United States, the TIN can be a Social Security Number (SSN) for individuals or an Employer Identification Number (EIN) for businesses. TINs are essential for filing tax returns, opening bank accounts, and applying for loans. They help streamline the tax process and prevent fraud. Each country may have its own system for assigning TINs, but the primary purpose remains the same: to identify taxpayers accurately.