A common charecteristic of web mapping applications is the ability to show information related to the features the map contains. By feature we mean any real phenomenon or aspect we can visually represent with points, lines, polygons, and so on.
Of course we can select a feature, retrieve its associated information and show it anywhere in our application layout, but the most common way to show it is by using popups.
divelement to hold the map:
<div id="ch3_popups" style="width: 100%; height: 100%;"></div>