When you apply to colleges in the United States, you will be required to provide documents that you create yourself. One of these documents is a Statement of Purpose.
For many, this will be a document unlike any you have yet created. The purpose of your statement of purpose is to razzle dazzle the committee. You need to answer the question "Why do I stand out of the crowd when applying to their program?" You talk about YOU. You talk about your unique life experience that led you to this career path. You talk about YOUR achievements, struggles and how you overcame them to get to where you are today. You talk about how these aspects of your uniqueness will add value at their institute.