The glass is broken or shattered
A storm, a stray ball, a rock from a mower, a slammed door or an attempted break-in. Whatever caused it, an open pane means rain, insects, animals and anyone outside can get in, and there is sharp glass around your family. This is the situation where the priority is securing the opening first and installing the new glass right after.
The glass is cracked but still in place
People often live with a crack for months, and it is worth knowing what happens next. A crack does not stay still. Temperature swings make glass expand and contract, so the crack grows a little every hot afternoon and cold night until the pane finally gives way, usually with no warning. Cracked glass is also much weaker, so a light knock is enough to break it. Replacing it while it is still one piece is safer and cheaper than cleaning up after it falls.
The glass is fogged or has moisture between the panes
If the haze is inside the glass where you cannot wipe it, the seal on the insulated unit has failed. In most cases the sealed glass unit can be replaced inside your existing window, which is far cheaper than a new window.
The glass is single-pane and the room is uncomfortable
Old single-pane glass gets hot in a Georgia summer and cold in winter, and the room next to it follows. Upgrading to insulated glass in a sound existing frame is a practical middle ground between doing nothing and replacing the window.
You want privacy or less glare
Bathroom, front door and street facing windows often need obscure, frosted or textured glass. It gives you privacy without blocking the daylight, and it is a simple swap.
Scratched, pitted or hazy glass
Years of hard water, pollen and mineral deposits can etch into the surface so it never looks clean again. If cleaning no longer works, replacing the glass restores the view.