The first thing that we need to understand about anything dealing with programming is the concept of variables. If you have taken algebra, then you know that variables are. If you haven't, then you are about to learn. A variable is just some letter or word that has a variable meaning. In other words, the value of that letter or word can change.
Variables can be anything, as long as the first character is alphabetic.
Notice that when we use spaces, we must insert an underscore instead of just a space. Variables are always numeric. We can either assign them a specific value, or we can leave them empty, to be filled in by input from a user. Lets say that we wanted to write a script using variables that would do some calculations for us. In this case we will figure how many seconds are in a number of hours.