Modern computer systems (CS) consist of two parts: hardware and software. Hardware is any electronic or mechanical part. Software is a set of instructions called a program, which tells the computer system what to do. Thus the program is a sequence of instructions (commands) describing the algorithm for solving a problem. Special programming languages are used for program development. Classification of the software is presented in figure 3.1.

Figure 3.1 – Classification software

The software of modern computers includes many programs - from gaming to scientific ones. The software is an integral part of the computer system. It is a logical continuation of technical means. The scope of the computer is determined by the software created for it. Software for its intended purpose is divided into system, tool and applied software.

System software includes operating systems (OS) and service programs. The main part of the system software is the operating system.

Operating system - a set of programs designed to manage the hardware of the computer and the organization of interaction with the user.

Service programs provide the user with additional services in working with the computer and extend the capabilities of operating systems. In terms of functionality, the service programs can be divided into:

- protecting data from destruction and unauthorized access;

- restoring data;

- accelerating data exchange between the disk and RAM;

- archiving-unarchiving;

- antiviral means.

By the way of organization and implementation, the service programs can be represented by: shells, utilities and stand-alone programs. The difference between shells and utilities is often expressed only in the universality of the former and the specialization of the latter.

Instrumental software is a set of programs designed to develop software applications and system software. The software is designed to help programmers in their work, to help software development managers in their efforts to control the development process and the products they receive.

At present, programming systems use Delphi, Visual Basic, C #, Java, and others. They are object-oriented programming languages ​​(OOP). The advantages of these languages ​​include the ability to create applications for working on computer networks, the Internet, as well as the ability to work with various programming elements as objects.

The OOP views programs as a collection of related objects. Objects are characterized by properties and methods. Objects respond to events (pressing a key, clicking a mouse button, opening a form, etc.). The programming process is reduced to operations with object properties and calling their methods. All these actions occur when the corresponding events are initialized. A programmer can create his own objects and assign them properties and methods.

The basic principles of OOP can be formulated as follows:

- everything is an object;

- objects exchange messages;

- Ability to write code used by many applications;

- every object is a representative of the class;

- the class defines the behavior of the object;

- classes are organized in a single hierarchical structure.

The following specialized functions are characteristic for the tool software:

1. Creation of the text of the program being developed using the programming language.

2. Translation of the text of the created program into machine-oriented code, available for execution on the computer. In the case of a significant amount of the created program, it is divided into separate modules and each of the modules is translated separately.

3. Connection of individual modules into a single executable code, with observance of the necessary structure, ensuring coordination of interaction of separate parts among themselves.

4. Testing and control of the created program, identifying and eliminating logical and syntactic errors, assessing the operability and effectiveness of the created program.

Application software is designed to solve problems in specific subject areas: scientific and technical, economic, engineering, design, etc. Thus, each application program is designed to solve a specific task in a specific application (for example: office programs, accounting programs, publishing systems, graphics packages, etc.).

Application software can be conditionally divided into general and special purpose programs.

General programs are universal software products designed to automate a wide range of user tasks.

Special purpose programs are designed to address the narrower professional tasks of different subject areas (architecture, construction, music and film industry).

General programs have a wide range of functions and, as a rule, are used by many users. General-purpose applications include:

- text editors (MS Word, Word Perfect, etc.);

- spreadsheets (MS Excel, Lotus 1-2-3, etc.);

- DBMS (MS Access, Oracle, etc.););

- graphic editors (Corel Draw, Adobe Photoshop, etc.);

- Presentation systems (MS Power Point, Freelance Graphics, etc.);

- electronic dictionaries and translation systems (Socrates, Lingvo, etc.);

- publishing systems (Page Maker, Venture Publisher, etc.).

Special-purpose programs are oriented to work in a special field of professional activity. Special application programs include:

- expert systems;

- decision support systems;

- Authoring systems.

General-purpose programs are often integrated into application software packages to automate office activities. For example, office packages Microsoft Office, StarOffice, etc.

The most popular are programs designed to work with texts - text editors and publishing systems. A great popularity acquired programs for processing graphics information. Computer graphics is currently one of the fastest growing areas of software. It includes the input, processing and output of graphic information (drawings, drawings, photographs, pictures, texts, etc.) using computer hardware. Different types of graphic systems allow you to quickly build images, enter illustrations with a scanner or video camera, create animation clips.

To perform calculations and further processing of numerical information, there are special programs - spreadsheets. In the process of the activity of any specialist, it is often required to present the results of the work in the form of tables, where one part of the field is occupied by the initial data, and the other by the results of calculations and graphical analysis. Typical for them is a large amount of processed information, the need for multiple calculations when changing the original data. Automation of this routine work and engaged in spreadsheets.

Database computer systems (DBMS) are used for computer processing of databases. The latter are a set of programs needed to create, process, and output database records. There are several types of databases: hierarchical, network, relational.

Application software also includes special-purpose software. At the present time, various special purpose software systems are created, designed for the work of specialists in a certain subject area. Such programs are called authoring systems. The author's system represents an integrated environment with a given interface shell, which the user can fill with the information content of his domain.

Expert systems have become widespread among such systems. Such programs behave like an expert in some narrow applied field. Expert systems are designed to solve problems with uncertainty and incomplete initial data, which require expert knowledge for their solution. In addition, these systems should be able to explain their behavior and their decision.

The main difference of expert systems from other programs is their adaptability, i.e. Variability in the process of self-education. Expert systems, which are the basis of artificial intelligence, are widely used in various fields of science. For example, in medicine for diagnosing, analyzing electrocardiograms, determining methods of treatment, in technology for troubleshooting technical devices, tracking spacecraft and satellites, in political science and sociology, forensics, linguistics, etc.