Fluency in reading is best described as:

Fluency in reading encompasses the ability to read text accurately and quickly, which is essential for comprehension. When a reader can recognize words effortlessly and read at a natural pace, they can focus their cognitive resources on understanding the meaning of the text rather than struggling with decoding individual words. This fluency leads to smoother reading, which facilitates better comprehension and retention of information.

While understanding complex texts, word recognition, and vocabulary improvement are important components of reading development, they do not solely define fluency. Each of these areas contributes to a reader's overall literacy skills, but the hallmark of fluency specifically lies in the proficient and rapid execution of reading itself. Thus, the essence of fluency is captured best by the ability to read accurately and quickly.