Once you have a use case description, you can analyze the use case to begin identifying some of the elements that will play a part in the system. One way to start is to look for all of the nouns in the use case description to see which ones seem to refer to important elements of the system. Each time you find an important idea in the use case, you can classify it as one of the following design elements (see Requirements model elements for more information on these elements):
Now, let's take a look at the text of the Adding a book use case to see what other design elements it refers to.