A variable is a container that holds information. The container itself is always the same, but the contents can change. By changing the value of a variable as the movie plays, you can record and save information about what the user has done, record values that change as the movie plays, or evaluate whether some condition is true or false.
Variables can hold either numbers or strings of characters. Typical types of information you can store in a variable include a URL, a user's name, the result of a mathematical operation, the number of times that something occurred, or whether a button has been clicked. Each movie and movie clip has its own set of variables, with each variable having its own value independent of variables in other movies or movie clips.
Variables in Flash do not have to be explicitly defined as holding either a number or a string. It interprets the data type as an integer or string accordingly. See also Emulating arrays.