Can you put AVI files on iPhone?

Is it possible to put avi files on iphone or does it have to be in mp4 format?

I have tried this with my ipod touch and it does not work.iDevices require a specific filetype (.mp4). You will need to convert it. My favorite program for this task is handbreak. It has a simple user interface (although it can be quite daunting for people new to video converting). And if you ever get stuck, it has excellent documentation online. And the feature I love most is that you can send it commands through the command line. I used to have a setup where a script would activate every time a new file was placed in a folder (by bittorent or wxdownloader) and send the video filename to handbreak which would then automatically convert it and copy it to my media hard drive and my "automatically add to iTunes", which in turn would be wirelessly synced to my ipod at around 2:00 AM and ready to go when I wake up. Hope this helps!

Yes you can. MP4 is a higher definition format and avi is often lower quality. You can use both! If you want to know more on the Apple iPhone 5 and it's digital music locker then you should read this article: http://bestsmartphone2011.org/top-10-cell-phones-in-2012/