Payment Card Industry Data Security Standard (PCI DSS) is a set of 12 requirements that all businesses who handle credit or debit card payments must comply with. This is relevant to both offline and online selling.
It provides business best practice guidelines to establish a "minimum security standard".
The 12 requirments fall into the following 6 categories:
- Build and Maintain a Secure Network
- Protect Cardholder Data
- Maintain a Vulnerability Management Program
- Implement Strong Access Control Measures
- Regularly Monitor and Test Networks
- Maintain an Information Security Policy
For more information: https://www.pcicomplianceguide.org/