What is PCI Compliance and why is it so important?

With regards to information security, PCI stands for the Payment Card Industry.  PCI Data Security Standards (PCI DSS) help ensure financial data security.  PCI Compliance ensures that organizations that deal with credit card and payment card data are taking proper measures to protect customer financial data.  If breaches are found on systems that are not PCI compliant, credit card companies have the ability to levy significant fines on the offending parties.