The GMAT scoring pattern consists of a cumulative Quant and Math score which is out of 800. The essay score called AWA is out of 6 and is reported separately and does not contribute to the 800 figure. So, it doesn't affect your score out of 800 but does get reported to the schools. Some schools ignore it - some look at it as corroborative evidence.
Note that your entire essays are sent to the schools/orgs as part of the official score that you want to send an official score report to. The schools can, if they choose to, read the essay you wrote.
Thanks for the explanation.