A Web Part in SharePoint is basically a widget that performs a particular task. In a regular SharePoint Page one might have at least 3-4 web parts. There may be times when you might want to add a new Web Part to a page and place it in a particular order. There is a way in which this can be achieved.
First you have to Edit the Page and then add the Web Part. The next step is to go to the Web Part Properties where a new window would pop up. In the Properties window, expand the Layouts Tab. Now you have to enter a value under Zone Index. Zone Index basically controls the order of the Web Parts from top to bottom. If the Zone Index has a value 0, it is top most Web Part. As the Value Increases, the position of the web part would go lower.