SSL Certificates are small data files that digitally bind a cryptographic key to an organization's details. When installed on a web server, it activates the padlock and the https protocol (over port 443) and allows secure connections from a web server to a browser. Typically, SSL is used to secure credit card transactions, data transfer and logins, and more recently is becoming the norm when securing browsing of social media sites.
Why SSL? As a web developer, I have come across many customers who ask "Why do I need SSL? What will it do for me?" This is an important question for anyone involved in the web to understand. SSL is the backbone of our secure Internet and it protects your sensitive information as it travels across the world. It keeps the Internet from being ruled by anarchists and criminals and provides many direct benefits to you and your customers.
Servers and browsers do encryption ranging from a 40-bit secret key to a 128-bit secret key, that is to say '2 to the 40th power' or '2 to the 128th power'. Many people have heard that 40-bit is insecure and that you need 128-bit to keep your credit card info safe. They feel that using a 40-bit key is insecure because it's vulnerable to a "brute force" attack (basically trying each of the 2^40 possible keys until you find the one that decrypts the message).
Encryption is a mathematical process of coding and decoding information. Encryption ensures that information is scrambled in transit so that only the intended recipient can decode it. The number of bits (40-bit, 56-bit, 128-bit, 256-bit) tells you the size of the key. Like a longer password, a larger key has more possible combinations.