An Employer Identification Number (EIN) is a unique nine-digit number assigned by the Internal Revenue Service (IRS) to business entities operating in the United States. It serves as a tax identification number for businesses, similar to a Social Security number for individuals.
Obtaining an EIN is crucial for various business operations, such as opening a business bank account, filing taxes, and hiring employees. Historically, businesses had to apply for an EIN in person or by mail, but the IRS now allows online applications through its website.