You don’t need to open up a Nokia smartphone to be able to install or customize the device according to your liking. Nokia phones mostly run the Symbian OS and it offers great usability and openness. You can personalize the look and feel of your phone, you can install plenty of applications without the need to jailbreak the phone, you can sign unsigned apps for Nokia, you can format or hard-reset your device and much more.
Symbian OS (Symbian 3, Anna or Belle) may not beat Android OS when it comes to power, openness and support but people who prefer openness and plenty of apps to choose from, will either get a phone that is Symbian-based or Android-based.
If you are a long time customer of Nokia, you probably know how Nokia phones work but if your family and friends are new Nokia phone users, you can share this page and let them bookmark it. Some of these guides may also give them confidence to configure the phone without the need to ask for your help. Symbian-based phone users may also learn how to keep their phone up-to-date and fix known bugs in the old version of the firmware.