The Skimming technique´s purpose is to identify the main idea of a text by quickly overlooking it. One of its characteristics is to review different elements of the text like the title, the epigraph, figures, and maps.
Another strategy of skimming is to quickly read the first and last paragraph or the first and last phrase of each paragraph.
It differs from the scanning technique because in this one the reading is more slowly. You´re looking for details in the text.
Skimming is more used for reading for pleasure while scanning is more used for studying for exams.
