SSL is used if the information to be transmitted is very important and requires increased security. For example, online stores, internet banking, serious e-mail systems, Internet fax and Internet telephony.
SSL is a cryptographic protocol. Cryptography is a mathematical process in which information is encoded and decoded. The protocol ensures that the information transmitted from the server to the client computer is cached, so if the information is intercepted, it can not be read and it is not possible to change the information. There are different length keys (40-bit, 56-bit, 128-bit, 256-bit) and the longer the key, the more variations.
SSL certificates can both be bought and shipped independently. Information cryptography requires two keys - public and private. Public key information is enclosed, private is duplicated.
Self-generated certificates are commonly used if the testing process is still in progress, or you trust the circle of individuals who will use your information resource. When you open the information resource that has the self-generated SSL certificate, you must count with the additional statement that the certificate is self-generated.
In return, for purchased SSL certificates, its issuer guarantees that the public key is real.