What is Linux?

According to www.webopedia.com:

" A freely-distributable open source operating system that runs on a number of hardware platforms. The Linux kernel was developed mainly by Linus Torvalds. Because it's free, and because it runs on many platforms, including PCs and Macintoshes, Linux has become an extremely popular alternative to proprietary operating systems.

According to http://en.wikipedia.org/wiki/Linux

Linux is a computer operating system and its kernel. It is one of the most famous examples of free software and of open-source development: unlike other major operating systems (such as Windows or MacOS), its underlying source code is available to the public and anyone can freely use, modify, and redistribute it.

The term Linux strictly refers to the Linux kernel, but is commonly used to describe entire Unix-like operating systems (also known as GNU/Linux) that are based on the Linux kernel combined with libraries and tools from the GNU project. Linux distributions often bundle large quantities of software with the core system, and over 300 distributions are available [1].

Initially, Linux was primarily developed and used by individual enthusiasts. Since then, Linux has gained the support of major corporations such as IBM, Hewlett-Packard and Novell for use in servers and is beginning to make inroads into the desktop market. Proponents and analysts attribute this success to its vendor independence, low cost, security, and reliability.

Linux was originally developed for Intel 386 microprocessors and now supports a variety of computer architectures. It is deployed in applications ranging from personal computers to supercomputers and embedded systems such as mobile phones and personal video recorders. "

What is Unix and what's the difference to Linux?

Linux is free, certainly cheaper than Unix.  Unix is a commercial system and was around before Linux. It still exists

How easy is it to use?

This falls in to the "how long is a piece of string" category.  It depends on what you want to do and what your previous experience is.  It can, and ultimately should be, at least as easy to use as Windows can be - ie point and click.  (But even this might provoke a debate about how "dumbed down" something should be to be easy to use - some people can't even use a VCR to record a programme aired at some future time.  Then again, some manuals are not very inviting to be read.)

How do you pronuounce it?

According to webopedia (http://www.webopedia.com) Linux is pronounced lee-nucks or lih-nucks.

Although this reminds me of a joke that runs  like this:

Tourist: "How do you pronounc Hawaii? Is it is Ha-wy-ee or Ha-vy-ee?

Native: "Ha-vy-ee"

Tourist: "Thankyou"

Native: "You're Velcome" !