Viewable Browser Space
Advertisements and content associated with each page load can appear either within or outside the viewable space of the browser on a user’s screen—i.e., that part of the page within the browser that a user can see. This is similar to the concepts once referred to as ‘Above the Fold’ (i.e., within the viewable browser space) and ‘Below the Fold’ (i.e., outside the viewable browser space).
The ‘fold’ was traditionally considered to be where the initially-loaded viewable space of the page ends – so advertisements and content above the fold were considered likely to be viewable upon load, and for content below the fold, it was considered necessary to scroll to in order for that content to be viewable. In reality, the location of the fold, and consequently the viewable status of advertising and content, is variable based on the browser settings of the user (resolution, font size, window size, etc.) and there are generally four locations (top, bottom, left and right sides) where advertising and content may be cut-off from being viewable based on user actions and settings. Upon initial page load, advertising or content placed at the top and left side of the page is most likely to be viewable, however this can change if content or ads are obscured by overlays or with further user action (scrolling*) coupled with latency; therefore, placement and viewable status are separate attributes to be assessed .
(*Note: this latter comment on ‘scrolling’ is significant for the growing trend for continuous page feeds, such as those seen in popular social media sites, where a substantial portion of the content is rendered on a single page that continues to load as a user scrolls through the content.) 
Return to V