Answer:
Reading is a cognitive process that involves connecting symbols (i.e. letters) onto the correct corresponding sound, in a process known as decoding. After decoding you must then connect this mapping to the meaning of the word/sentence (aka comprehension). In order to be a successful reader one must be able to read fluidly at a steady pace and with the right intonation, while comprehending the intended message of the text.
The development of reading (aka developmental reading) is a gradual process, the goal of which is fluid reading. First, a child begins to learn the correct mapping between the letters and the sounds of words. They then begin to incorporate the meanings of words. As a child's vocabulary grows, so does their ability to read in a fluid manner as well as their ability to comprehend text.