Trusted Certificate Authorities (CAs) are organizations that are trusted to issue SSL/TLS certificates for websites and online services. These CAs are recognized by web browsers and operating systems, which include their root certificates in their trust stores. When a web browser or device encounters an SSL/TLS certificate issued by a trusted CA, it validates the certificate’s authenticity and establishes a secure connection with the website. Here are some well-known trusted CAs:

1. Let’s Encrypt: Let’s Encrypt is a free, automated, and open Certificate Authority that issues SSL/TLS certificates at no cost. It is operated by the Internet Security Research Group (ISRG) and is widely used by websites to secure their connections.
2. DigiCert: DigiCert is a leading provider of SSL/TLS certificates and digital security solutions. It offers a wide range of certificate types, including single domain, wildcard, and multi-domain certificates, with various levels of validation.
3. Comodo CA (now Sectigo): Comodo CA, now part of Sectigo, is another major provider of SSL/TLS certificates. It offers a variety of certificate types, including domain validation (DV), organization validation (OV), and extended validation (EV) certificates.
4. GlobalSign: GlobalSign is a trusted Certificate Authority that offers SSL/TLS certificates, digital signatures, and other PKI solutions. It provides a range of certificate options for different use cases, including website security, document signing, and code signing.
5. Entrust: Entrust is a trusted provider of SSL/TLS certificates, PKI solutions, and identity management services. It offers a variety of certificate types, including SSL/TLS certificates for websites, email security certificates, and code signing certificates.
6. GoDaddy: GoDaddy is a well-known domain registrar that also offers SSL/TLS certificates for website security. It provides both standard SSL certificates and premium SSL certificates with additional features.
7. Thawte: Thawte is a long-standing Certificate Authority that offers SSL/TLS certificates with various levels of validation. It is known for its global reach and trusted certificates.

These are just a few examples of trusted Certificate Authorities. There are many other CAs that are recognized and trusted by web browsers and operating systems, each offering a range of SSL/TLS certificate products and services to meet the security needs of website owners and online businesses.