In simple terms, domain is the name or the identity for your website. This domain is registered at a central registral so that its unique and is one for each website. Domain consists of multiple words and symbols seperated from its extension by a dot. eg: bodhost.com, here bodhost is the domain and .com is its extension. There are many choices for the extensions that you can choose depending on the area or the segment that you wish to target, eg: .com, .net, .org, .info etc.
Anyone can register a domain through a domain registrar. You just have to contact a domain registrar and check if the desired domain name is available. If its available, you can pay the applicable registration charges and get a domain for yourself.
The basic function of Secure Socket Layer (SSL) is of encryption. Imagine that you are sending a letter to your friend and you are not sure that your friend will be the first person to receive the letter. Here you use code language so that even if someone else opens it, he won't understand the message.
This is exactly what SSL does with your information/data. Your data is encrypted before it moves across the Internet from your computer to the destined computer. Once it reached the destined computer, its decrypted. This process allows the data a safe passage in the travel across the start point to end point.
In simple terms back-up is a copy of a file, program or data that is stored separately from the original. These days due to technological advancements and the dependency on machines back-ups are very essential in order to safeguard your crucial and important data.
The reason one should always opt for a backup is because you cannot forecast when your computer or the disk on which the data is stored will be damaged. As the saying goes, precaution is better than cure, its always better to backup data first hand rather than to regret after losing your data.