Boxes 1 to 3 are positioned according to the normal flow.

Boxes 2 to 3 are positioned according to the normal flow, but box one has a position attribute with a left value of 0 pixels and a top value of 0 pixels. Note that this is the same as if it were not being positioned so it seems that it is positioned relative to its expected position if we hadn't not specified the position attribute.

Again, boxes 2 to 3 are positioned according to the normal flow, but box one has a position attribute with a left value of 400 pixels and a top value of 200 pixels. We can see that the box has moved over to the left and down, relative to where it would ordinarily be if we didn't specify a position attribute, in other words, where it would be if it were following the default flow. Note that the other blocks have not moved to occupy the space which box 1 occupied previously.

Note that the posisitons are all expressed from the left and the top of the viewport.