1. What Do Computers Do?
A computer system is
The major hardware components:
processors
memory
peripheral devices
Most software falls into two categories:
operating systems
applications
an integrated collection of hardware and software components.

2. Ways of Interacting with Computers
Two major types of interfaces:
GUI
text-based
Algorithm
Algorithm is a step-by-step procedure for solving a problem
It can be expressed in:
natural language
programming language
pseudocode

3. Executing a program
Two approaches to execute a program written in a high-level language:
compilation
interpretation
Executing a Java program requires:
Compiling the program to get bytecodes instructions
Using interpreter to execute bytecodes.