The Employer Identification Number (EIN), also known as the Federal Employer Identification Number (FEIN) or the Federal Tax Identification Number, is a unique nine-digit number assigned by the Internal Revenue Service (IRS) to business entities operating in the United States for the purposes of identification. When the number is used for identification rather than employment tax reporting, it is usually referred to as a Taxpayer Identification Number (TIN), and when used for the purposes of reporting employment taxes, it is usually referred to as an EIN.
Your business needs to apply for an EIN in-order to open a bank account, among other uses.
When registering a new business in the US, once you get your corporate paperwork back from the state, you can apply for an EIN (employer identification number) with the IRS here: https://sa.www4.irs.gov/modiein/individual/index.jsp