What is "viewport"
The Viewport is a polygonal visualization region in computer graphics, or a term used for optical components. It has several definitions in different contexts.
In 3D computer graphics it refers to the 2D rectangle used to project 3D scenes from the point of view of a virtual camera. A viewport is a region of the screen used to display a portion of the total image to be shown.
In web browsers, viewport (in this context translated into Portuguese will be - display window) is the visible part of the whole document. If the document is larger than the display window, the user can move the display window down or up by scrolling the page using the scrollbar (scrollbar).