Reading is an active process that involves a transaction between the reader's background knowledge and the text. It is constructive, as readers use their schema to make inferences and derive meaning. Reading comprehension depends on the reader's prior knowledge, ability to understand the language of the text, and ability to understand the message. Readers use both top-down and bottom-up processing, applying their expectations while taking in elements from the text. Multiple types of knowledge, such as syntactic, morphological, world, and topic knowledge, help readers make sense of a text.