There are hundreds of different materials that can be used in window frames. In theory, there’s nothing stopping you from using iron for your windows if you can keep it from getting wet. But for general-purpose, the five most commonly used window materials in the world right now are aluminum, hardwood, uPVC (aka vinyl), steel, and glass fiber.
Metals like steel and aluminum are durable, but they also conduct heat, which compromises home insulation. Hardwood, uPVC, and glass fiber are all good at insulation. However, wood is liable to crack and rot over time. Glass fiber is relatively a novel material, which means it is often expensive, and maybe unreliable between manufacturers. Meanwhile, uPVC offers good value and low need for maintenance, but they are also relatively weak. If you are going for uPVC windows, make sure to use ones that are reinforced with steel and double-glazed windows to protect your home.
I would recommend reinforced uPVC windows to any friend who is shopping for new frames, but what material is best for you will depend on your needs. And if you want to install double glazed windows, click this link. It’ll help you find double glazing Crystal Palace.