What is in an IPSW file? I know that an IPSW is an iOS firmware restore file. When you want to install a beta firmware, Apple ships these. This website stores all old iOS versions in that format.

What exactly is in an IPSW file and in what format?

Can I view the files in it? Do I use a hex editor, or something else? Is an IPSW like a zip file (like .app or .bundle), or is it binary encoded or encrypted?
The IPSW file type is primarily associated with 'iPhone/iPod' by Apple Inc.. This is a firmware update file for the iPhone. The file is a renamed .ZIP file. If you unZIP it you will see a file called MANIFEST.PLIST and a file without an extension but with a version number in the name, e.g., Firmware-14.5.3. This file is the firmware image.

Source http://filext.com/file-extension/IPSW