History and Philosphy

UNIX was conceived in 1969 by Ken Thompson at AT&T Bell Laboratories who wanted to create a flexible software development environment.
UNIX became successful for development work at AT&T in the early 70's, and also became popular at a large number of colleges and universities.
Although it was originally written in assembler, it was later rewritten in the 'C' language, which allowed it to be easily ported to other hardware platforms (portability).
Two distinct 'flavors' of UNIX evolved over time - AT&T System V and Berkeley UNIX.

You will be using bash, which is the version of shell running under Ubuntu LINUX.
You will be exposed to other "flavors" of Linux which is good practice to see what is similar and what might be different.

You may be surprised to hear that an operating system "has a philosophy", but learning LINUX will be much easier and possibly less frustrating if you understand its philosophy.
The basic philosophy of LINUX is to have small pieces (commands), each of which do 1 thing.
If you want to do more complicated tasks, you will put commands together. You will do this by having the output of one command become the input to another command (called using pipes) and often will write LINUX programs (called shell scripts) to automate tasks.
This means that good LINUX users will become programmers who will write shell scripts at the drop of a hat (more on this later!).
On the negative side, this philosophy makes LINUX difficult for beginners to learn. It is not "point and click" because it is meant for programmers and you will have to learn many commands to even get started.
On the plus side, this means that once you learn some basic LINUX commands and how to get around a LINUX machine, you can do just about anything.
So, LINUX is not particularly easy to learn, but once you learn it, it is a very powerful, user-friendly environment in which to work.