C/C++
C is the most commonly used programming language for writing operating systems. Unix was the first operating system written in C. Later Microsoft Windows, Mac OS X, and GNU/Linux were all written in C. Not only is C the language of operating systems, it is the precursor and inspiration for almost all of the most popular high-level languages available today.
The primary design of C is to produce portable code while maintaining performance and minimizing footprint, as is the case for operating systems or other programs where a "high-level" interface would affect performance. It is a stable and mature language whose features are unlikely to disappear for a long time and has been ported to most, if not all, platforms. One powerful reason is memory allocation. Unlike most computer languages, C allows the programmer to write directly to memory. Key constructs in C such as structs, pointers and arrays are designed to structure, and manipulate memory in an efficient, machine-independent fashion. In particular, C gives control over the memory layout of data structures. Moreover dynamic memory allocation is under the control of the programmer, which inevitably means that memory deallocation is the burden of the programmer. Languages like Java and Perl shield the programmer from having to worry about memory allocation and pointers. This is usually a good thing, since dealing with memory allocation when building a high-level program is a highly error-prone process. However, when dealing with low level code such as the part of the OS that controls a device, C provides a uniform, clean interface.
Some languages require total and complete detail about everything. C and C++ are such languages, and are called low-level languages. Other languages will make all sorts of assumptions, and this lets the programmer specify less detail. Python and Basic are such languages, and are called high-level languages. In general, high-level languages are easier to program but give you less control. Control is sometimes important, for example if you want your program to run as quickly as possible. Most of the time total control and speed aren't necessary, and as computers get faster high-level languages become more popular. Here we will deal exclusively with high-level languages.
Before you begin your journey to understand how to write programs using C++, it is important to understand a few key concepts that you may encounter. These concepts are not unique to C++, but are helpful to understanding computer programming in general. Readers who have experience in another programming language may wish to skim through this section, or skip it entirely. There are many different kinds of programs in use today. From the operating system you use that makes sure everything works as it should, to the video games and music applications you use for entertainment, programs can fulfill many different purposes. What all programs (also called software or applications) have in common is that they all are made up of a sequence of instructions written, in some form or another, in a programming language. These instructions tell a computer what to do, and generally how to do it. Programs can contain anything from instructions to solve math problems, to how to behave when a video game character is shot in a game. The computer will follow the instructions of a program one instruction at a time from start to finish. Another thing true of all computer programs (or most programs, rather) is that they solve problems and perform tasks. Say hello to the world. Paint a button on the screen. Calculate 26*78. Drive the car. Fortunately or not, computers must be taught how to perform these tasks. In other words, they must be programmed.