Final answer:
The official name of Barack Obama's signature social welfare policy is the Patient Protection and Affordable Care Act, also known as Obamacare.
Step-by-step explanation:
The official name of the signature social welfare policy of Barack Obama's presidency is the Patient Protection and Affordable Care Act, commonly referred to as Obamacare. This landmark legislation aimed to provide all Americans with access to affordable health insurance, mandate that everyone in the United States had some form of health insurance, and reduce the overall costs of healthcare.
The act was signed into law on March 23, 2010, and despite facing political opposition, the act represented a significant overhaul of the U.S. healthcare system and aimed to extend insurance coverage to millions of uninsured Americans.