Unofficial quick counts are a parallel counting mechanism that it is important to distinguish from exit polls. A quick count is a partial count of actual results (whereas exit polls are simply a species of opinion poll), used to predict the actual full result. A quick count may often be used as a means of forestalling any manipulation of the results. For the media, of course, the interest is similar to an exit poll in that it enables them to run an early results story.
What they have in common with opinion polls, is the need for the media to report with precision what the count actually measures - in other words, what sample it draws upon and the degree of accuracy that can be expected.
See Quick Count of Voting Result for a fuller discussion
