PCI DSS stands for Payment Card Industry Data Security Standard and is a set of requirements which are designed to ensure that all companies that accept, process, store or transmit credit card information maintain a secure environment.
There are 12 broad requirements for PCI DSS compliance, which are grouped together under six headings as shown below. Each of these headings represents a whole raft of specific actions. For a more in-depth look at what is needed, The Security Standards Council have produced a reference guide.