new jailbreak for iOS 8.3

What do I think? I think it's wonderful, that's what! Can you share the link, and maybe an accessibility guide to setting it up? Thanks!

Before I start jailbreaking, I have a few questions:
1. What is the differences between the tethred and untethred jailbreak?
2. Before I start the jailbreak, do I need to backup something first with iTunes?
3. After my phone is jailbroken, what will happen to my phone?
And finally, can I restore my phone to it's original state?

First off, I'm not sure if the new iOS 8.4 can be jailbroken, but if you're still running 8.3 you should be good to go. Make sure you get the latest installer though, I think is 2.11.
Now as to your questions. I don't believe their even are tethered jailbreaks any more, but even if there are, avoid them. It means that every time you reboot your phone, you have to be "tethered," to your computer. I would never do it.
As far as what will happen to your phone, well just imagine all Apple's restrictions lifted. You can download music and ringtones and put them right in your regular music library, without iTunes. You can have folders within folders within folders. You can have up to eight slots in your dock instead of just four, and you can have 20 apps per page instead of twelve. Before Alex on the 6 came, I had learned to get the Siri voices to work with VO, but I am satisfied with Alex so don't need that any more. Plus, there are apps and tweaks on Cydia, the jailbreak repository, that you can't get in the app store. The most noteable is called Activator. It allows you to customize just about any imaginable gesture to just about any imaginable outcome, like shaking the phone to answer it. The sky's the limit.
Should you back up before jailbreaking? Highly recommended. Can you reset to default factory settings? I'm sure you can, but I don't have the foggiest how. Last time I tried doing it through iTunes and the phone froze up, so I had to plug it into my friend's mac book air, and that fixed everything. I'm sure there are easier ways, though, because people do it all the time.

thanks for the answer ken.
anyway, if my phone was jailbroken, can I send music, photos, videos or any other files via bluetooth? also, can I make my phone plays a sound when it is starting up and shutting down?

I don't think you can do the latter, but you can look in the cidia store for the former action as there must be an app for what you want.

I don't know if you can do the former, but you can definitely do the latter. There is a tweak called, I think, iStartupSounds or something like that. I'm not currently jailbroken so I can't just look. There are even ways, if you're savvy enough, to change system and voiceover sound effects. I know people who have all kinds of crazy sounds for VO events. Good luck with the jailbreaking. By the way, does the old jailbreak work on iOs 8.4?

Hi. Yes, the same people who made the iOS 8.3 jailbreak made one for iOS 8.4 for windows. There is also a jailbreak for Mac supporting iOS 8.3 and 8.4 called pp25