Software. Operating system

SOFTWARE
Software is the general term for the set of programs and data, which direct the hardware on what to do,it is the various kinds of programs used to operate computers and related devices.Softwares are subdivided into Application and System software.

• System software focuses on handling technical details.
• Application software focuses on completing specific tasks or application.

System Software
This software is designed to control and work with computer hardware.
These are programs expressly designed to make the computer more efficient and flexible

System files include libraries of functions, system services, drivers for printers and other hardware, system preferences, and other configuration files. The programs that are part of the system software include assemblers, compilers, file management tools, system utilites, and debuggers.
The system software is installed on your computer when you install your operating system. You can update the software by running programs such as "Windows Update" for Windows or "Software Update" for Mac OS X. Unlike application programs, however, system software is not meant to be run by the end user. For example, while you might use your Web browser every day, you probably don't have much use for an assembler program (unless, of course, you are a computer programmer).

Operating system
What is an operating system? An operating system is the most important collection of programms that runs on a computer.
OS manages the memory and processes, hardware, i.e. controles all computer's resources.
OS allows you to communicate with the computer without knowing computer's language
OS provides a pleasant and effective interface between the user and the hardware.
Without OS, a сomputer is useless.

The structure of OS consists of 4 layers:
Hardware
Operating System
System programs
Application programs

Types of OS
Multi-user
Multiprocessing
Multitasking
Multithreading
Embedded system

Operating Systems
The three most common operating systems for personal computers are
Microsoft Windows
Mac OS X
Linux.

Windows
Microsoft created the Windows operating system in the mid-1980s. Over the years, there have been many different versions of Windows, but the most recent ones are:
Windows Vista (2007)
Windows 7 (2009)
Windows 8 (2012)
Windows 10 (released in 2015)
Windows comes pre-loaded on most new PCs and nowdays it is the most popular operating system in the world.

Mac OS
Mac OS is a line of operating systems created by Apple. It comes preloaded on all new Macintosh computers, or Macs. All of the recent versions are known as OS X (pronounced O-S Ten), and the specific versions include El Capitan (released in 2015),Yosemite (2014), Mavericks (2013),
Mountain Lion (2012), and Lion (2011).

According to Statistics, Mac OS X users account for less than 10% of global operating systems—much lower than the percentage of Windows users (more than 80%). One reason for this is that Apple computers tend to be more expensive. However, many people do prefer the look and feel of Mac OS X over Windows

Linux
Linux (pronounced LINN-ux) is a family of open-source operating systems, which means they can be modified and distributed by anyone around the world. This is different from proprietary software like Windows, which can only be modified by the company that owns it. The advantages of Linux are that it is free, and there are many different distributions—or versions—you can choose from.