If you are a website developer or programmer, then it is often very tempting to make changes straight on to a live site rather than on a staging area. This can make jobs much quicker, but it can also be very risky and not a very professional what to work. For some smaller jobs, making changes directly on to the site can be the best option. For example, if you just wanted to adjust the font colour or one banner or to change the font size of the text in the navigation then you may choose to do it directly on the site. Even smaller jobs however can benefit from being done on a staging area as it gives you the opportunity to spot issues that may arise such as your navigation then pushing on to two lines for example.
It may be that your client wants changes done but they want to be able to see what they will look like or how an area will work before they decide whether they definitely want to go ahead with it. A staging area is the perfect place to do this and to allow then to have a play around with it before transferring it over to the live site.