The most common web technologies for improving security between browsers and websites are named SSL (Secure Sockets Layer), and its successor TLS (Transport Layer Security), identity management and authentication services, and domain name services allow companies and consumers to engage in secure communications and commerce. Several versions of SSL and TLS are commonly used today in applications such as web browsing, e-mail, internet faxing, instant messaging, and VoIP (voice-over-IP). There are various interoperable implementations of these technologies, including at least one implementation that is open source.