ONE POINT PERSPECTIVE IS A STYLE OF DRAWING THAT GIVES THE FEELING OF DEPTH BY MAKING ALL OBJECTS VANISH INTO ONE POINT SOMEWHERE IN THE PICTURE.
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SOME OBJECTS WHEN DRAWN APPEAR LARGER THAN THEY ACTUALLY ARE, FOR EXAMPLE, THE PICTURE ABOVE.
ONE POINT PERSPECTIVE IS USEFUL WHEN SKETCHING ROOM LAYOUTS LIKE THE IMAGE BELOW.

THE VANISHING POINT
THE VANISHING POINT (VP) IS THE POINT WHERE ALL THINGS MEET. ALL THE HORIZONTAL LINES WILL END AT THE VANISHING POINT.
SOURCE: www.ider.herts.ac.uk/school/courseware/graphics/one_point_perspective.html