Clearing Doubts on iPhone / iPad Jailbreaking

I've been asked recently by friends who own iDevices which are not jailbroken. They are curious enough to try it out but not without having their doubts on jailbreaking cleared first.



Here are some of their queries:
1. can I install new iOS updates after jailbroke?
2. will itunes still work with jailbreak?
3. what will happen to all my purchased applications?
4. can I un-jailbreak and return to the stock firmware?
5. does that mean I can get a lot more applications for free?
6. is it stable?

I will answer the above questions as best as I know of jailbreaking:
1. After jailbroke, all original functionalities remained the same. That means, you can still perform your installing of apps via iTunes, sync your music, videos using iTunes, upgrade your iOS firmware updates, versions using iTunes.

2. Refer to my answer number 1 above.

3. As explained in item 1, all original stuff are "business as usual", your purchased apps will remained purchased and entitled to free upgrade via iTunes if applicable. After jailbreak, all installed apps are left untouched and unmodified.

4. To "un-jailbreak", just use iTunes to restore to the lastest iOS version. iTunes will automatically restore the latest version downloaded from Apple server. After restored, just select "restore from backup" or similar option. This will reinstall (and copy all saved settings) all previously installed apps. Of course, you must have previously done a sync to backup these installed apps to your PC/Mac.

5. After jailbreak, basically, the whole root file system is read-writable and many hacks can be downloaded to allow modifying these filesystem files. One of the hack is to allow installing apps/games that people "cracked". The answer is Yes, you can get a lot more applications for "free". But I would say that is really some sort of piracy and I really discourage that.

6. As jailbreak adds some low-level codes to the filesystem, some jail broken apps/hacks may not have properly coded and may cause system crashes. So before installing these hacks, be sure to check out in the forums about any stability issues.