H4 visa is for the dependent family members of H1 visa holders who would like to join the H1 holder in the United States to stay for the H1 Visa period. Immediate family members like spouse and children under 21 yrs can qualify for this visa and can apply at the homecountry US Consulate. If you are applying for your visa along with your spouse, who is applying for H1 simultaneously, then you can submit both of your applications together. As a H-4 visa holder, you're not authorized to be employed in the US and are not eligible to get a Social Security Number. Although, you can get a drivers license, open bank account(s) and are eligible for an ITIN (Tax ID for IRS Tax purposes).