What is an Enrolled Agent?

From the National Association of Enrolled Agents (NAEA):

Enrolled agents (EAs) are federally-authorized tax practitioners who have demonstrated technical competence in tax law and are the only taxpayer representatives licensed to practice by the United States government. Only EAs, attorneys and CPAs may represent taxpayers without limitation before the IRS. EAs advise and represent taxpayers who are being examined by IRS, taxpayers who are unable to pay, and taxpayers who wish to avoid or recover penalties. EAs prepare tax returns for individuals, partnerships, corporations, estates, trusts and any other entities with tax-reporting requirements. Unlike attorneys and CPAs, who may or may not choose to specialize in taxes, all EAs specialize in taxation and are required by the federal government to maintain their professional skills with continuing professional education.