Comprehension is the understanding and interpretation of what is read. To be able to accurately understand written material, children need to be able to (1) decode what they read; (2) make connections between what they read and what they already know; and (3) think deeply about what they have read.
One big part of comprehension is having a sufficient vocabulary, or knowing the meanings of enough words. Readers who have strong comprehension are able to draw conclusions about what they read – what is important, what is a fact, what caused an event to happen, which characters are funny. Thus comprehension involves combining reading with thinking and reasoning.