Viewer
Viewer may refer to any of the following:
1. A program that allows a user to display a file type or multiple file types. For example, a viewer may be capable of allowing a computer user to display a word processor document without having the word processor program installed.
2. With a video or website showing videos, a viewer is one person who has viewed a video. For example, after you've watched a YouTube video, its total views are increased by one view. The website determines what it considers a view. For example, some websites may consider a view as someone who opened the video regardless of how long they watched the video. Other sites may require you to watch the whole video or a large percentage of the video before it is counted as a view. Sites like YouTube do not officially disclose what they consider a view to help prevent people from making fraudulent views.