EIN means Employer Identification Number.

This identification number is provided by the Internal Revenue Service (IRS) to every US business, whether incorporated or not, with or without employees. The EIN is a single nine digit number (in xx-xxxxxxx format) which constitutes, to some extent, the social security number of the company.

It is required by various parties, such as government agencies, providers, etc...

Before opening a bank account for your company you will need to apply for an EIN. All banks in the USA ask for the company's EIN before accepting to open a checking account.