If there were only one aspect of language that students could study (or that educators could teach), it would invariably be reading comprehension. Beloved reading comprehension, a friend to nearly every teacher of language. But what makes it so special? Why is it so revered by both students and teachers alike? To answer these questions, it helps to know just what reading comprehension is. Reading comprehension is defined as the level of understanding of a text. This understanding comes from the interaction between the words that are written and how they trigger knowledge outside the text. Humans are thought to have a set reserve, an established threshold for attention and absorption of information, commonly referred to as processing capacity. This being the case, it is generally believed that proficient reading depends on the ability to recognize words quickly and effortlessly. If word recognition is difficult, students use too much of their processing capacity to read individual words, which interferes with their ability to comprehend what is read.