Distinct in a simple SQL query : when executing queries in SQL I have been trying to figure out the following:
In this example,<br> 
SELECT DISTINCT AL.id, AL.name<br>
FROM albums AL

Why is there a need to specify distinct? I thought that the Id being a primary key was enough to avoid Duplicate results. Thanks in advance.

Edit: I have been using and learning SQL for a year but this concept I cannot grasp.