Without trust, no website or online service can succeed in the competitive online marketplace. This year has seen a spate of breaches that have targeted the systems of Certificate Authorities (CAs), the companies that prove websites and services are secure and safe to use. Some of these attacks have undermined the trusting relationship between users and even well-known online brands. The changing security landscape has demonstrated not all CAs are the same, and choosing the right CA is critical to running and maintaining a safe and trusted online business. This white paper looks at the role of CAs in web security, including what measures a CA can take to promote trust in its certificates and the criteria to consider when choosing the best CA for the job.