The Secure Socket Layer (SSL) is a protocol that uses encryption and authentication techniques to secure connections between clients and servers.
By encrypting data transfers between Symphony clients and servers, SSL virtually guarantees that if the data is intercepted enroute, it will be unintelligible without the relevant information required to decrypt it.
SSL also enables server authentication by using a certificate to validate its identity. This is especially important for preventing a 'man-in-the-middle' attack where someone actually pretends to be your server in order to gain access to sensitive material. SSL certificates ensure that the server you are connecting to is the server you intended to connect to.