SE tax is the employer share, and its a bit complicated. As a 1099, you are required to pay the full SE tax generally minus (a couple?) deductions. But then, you are allowed to deduct half of what you pay in SE tax from your income for regular income tax. The SE tax is also paid I believe only up to some income limit. Then, there's the Medicare tax on top of that, which is not income-limited.

Basically they are self-employment taxes, which is just the employer side of payroll taxes.