Mind the GAP
GAP stands for:
What is the text? How do you know?
In the exam, this is easy because you will be told where the text came from. Knowing where the document came from - eg a newspaper, a magazine, a website, a book etc - will help you to think about the intended audience.
Who is the text aimed at? How do you know?
A writer always has an audience in mind. Different styles of writing will be used for different audiences. You would probably not speak to your head teacher in the same way as you speak to your friends.
What does the text want you to do? How does the text make you do it?
All documents have a purpose - some entertain, some inform, some persuade and so on.
To answer these questions in detail, you need to think about 'Make a LIST'...
Make a LIST
LIST stands for: