HARDWARE AND SOFTWARE
A computer system also consists of hardware and software for its proper functioning. 
Hardware represents the physical and tangible components of the computer i.e. the components that can be seen touched. Input devices, CPU, floppy disk, hard disk etc. are examples of computer hardware.
Software represents the set of programs that can govern the operation of a computer system and make the hardware run. Software can be classified broadly in to three categories.
1. Operating system
2. Language processors
3. Application software.
Operating system and Language processors are combining called system software.
OPERATING SYSTEM
Hardware is nothing but finally designed machinery. A machine is ultimately machine only which is always made to work. In case of computers, it is either me if we do that or ‘some other’ which does it for us. This ‘some other’ is nothing but our own ‘operating system’.
An operating system is a program which acts as an interface between a user and the hardware i.e. all computer resources.
Operating system is just like our secretary. As the boss gives order to his secretary and the secretary does all the work. The secretary himself decides: How to do? ; What to do? ; When to do? ; The primary goal of an operating system is just to make the computer system convenient to use and secondary goal is to use computer hardware in an efficient manner.
An operating system is an important component of a computer system which controls all other components of computer system. Major components of computer system are:
1. The Hardware
2. The operating system
3. The Application program routines (compiler, linkers, database management systems, utility programs)
4. The Human ware (users)
Where hardware provides the basic computing resources, the application program routines define the ways in which these resources are used to solve the computing problems of the users and the operating system controls and coordinates the use of the hardware among the various application for the various users. 
The operating system performs the following functions:
(i) Provides the instruction to prepare user interface i.e., way to interact with user whether through typed commands or through graphical symbols.
(ii) Loads necessary programs (in to the computer memory) which are required for proper computer functioning. 
(iii) Coordinates how program works with the CPU, keyboard, mouse, printer, and other hardware as well as with other software.
(iv) Manages the way information is stored on and retrieved from disks.
There are various types of Oss – single user OS, multiuser OS, batch processor OS, multiprocessing OS etc.
As the names suggest, single user OS supports single user whereas multiuser OS can support multiusers. The batch processing OS processes the batches (groups) or jobs (processes) given to it) and multiprocessing OS in capable of handling multiple CPUs at the same time. 
LANGUAGE PROCESSORS
As programmer prefer to write their programs in one of the high level languages. However, however the computer does not understand any language other than its own machine language (binary language) therefore it becomes necessary to process a HLL program so as to make it understandable to the computer. The system programs which perform this very job are language processors. The language processors are given below:
(i) Assembler. This language processor converts the program written in assembly language in to machine language.
(ii) Interpreter. This language processor converts a HLL program in to machine language by converting and executing it line by line. If there is any error in any line, it reports it at the same time and program execution cannot resume until the error is rectified. Interpreter must always be present in the memory every time the program is executed as every time the program is run, it is first interpreted and then executed. For error debugging, interpreter, is very much useful as it reports the errors at the same time. But once errors are removed, unnecessary usage of memory takes place as it has to be present in the memory always.
(iii) Compiler. It also converts the HLL program into machine language but the conversion manner is different. It converts the entire HLL program in one go, and reports all the errors of the program along with the line numbers. After all the errors are removed, the program is recompiled, and after that the compiler is not needed in the memory as the object program is available.
Therefore if we combine interpreter and compiler, it gives the best combination for HLL program translation in to the object code. For the error removal interpreter can be used and after all the errors are removed the program can be compiled enabling the removal of the language translator from the memory.
APPLICATION SOFTWARE
This type of software pertains to one specific application. For instance, software that can perform railway reservation functions cannot prepare result for a school.
Application software is the set of programs necessary to carry out operations for a specified application.
These are the program written by the programmers to enable computer to perform a specific task such as inventory control, medical accounting, financial accounting, result preparation, railway reservation, billing etc. Application software can further be subdivided in to two categories. 
Customized application software – This type of software is tailor’s made software according to a user’s requirements. The software is developed to meet all the requirements specified by the user. However, this cannot be directly installed at any other user’s workplace as the requirements of this user may differ from the first one and software may not fit in the requirements of the new user.
General application software – This type of software is developed keeping in mind the general requirements for carrying out a specific task. Many users can use it simultaneously as it fulfills the general requirements.
STRENGTH AND WEAKNESSES OF A COMPUTER
As you see that computers are being used almost everywhere. Most of the areas have already starting working with the help of computers such as banking, railways, airways, airways, electricity billing, hotels, schools, colleges, shops, big stores, industries, defense, designing etc. etc. These areas were working without computers sometime before and the same type of task was being performed earlier also. What made them shift from manual working to computerized working? There must be some advantages of computers that attracted them. Indeed there are some big advantages or strengths of computers. These are as follows:
1. Speed. Computers are much faster as compared to human beings. A computer can perform a task in a minute that may take days if performed manually. A modern computer can execute millions of instructions in one second.
2. High storage capacity. Computer can store a large amount of information in very small space. A CDROM of 4.7 inch diameter can store all the 33 volumes of Encyclopedia Britannica and will still have room to store more information. Bubble memories can store 6,250,000 bits per square centimeter of space.
3. Accuracy. Computers can perform all the calculations and comparisons accurately provided the hardware does not malfunction.
4. Reliability. Computers can perform all the calculations and boredom or fatigue. Thus they are more reliable than human being.
5. Versatility. Computer can perform repetitive jobs efficiently. They can solve labour problem or do hazardous jobs in hostile environment. They can even work in the areas where human brain can err for instance observing motion of very fast moving articles. Also they can work with different types of data and information like graphic, audio, visual, characters etc.
Inspite of having all the above given characteristics, it does possess some limitations also that are strengths of human beings.
1. Lack of decision making power. Computer cannot decide on their own. They do not posses this power which is a great asset of human being.
2. IQ zero. Computers are dumb machines with zero IQ. They need to be told each and every step, however minute it may be.
These limitations of computers are characteristics of human beings. Thus, computer and human beings work in collaboration to make a perfect pair.
1. Lack of decision making power. Computer cannot decide on their own. Their do not possess this power which a great asset of human beings.
2. IQ zero. Computers are dumb machines with zero IQ. They need to be told each and every step, however minute it may be.
These limitations of computers are characteristics of human beings. Thus, computers and human beings work in collaboration to make a perfect pair.
Firmware. Like hardware and software, firmware is another term commonly used. Firmware is a prewritten program that is permanently stored in read-only memory. It configures the computer and is not easily modifiable by the user. BIOS (basic input output services) instructions are an example of firmware.
Liveware. It is the term generally used for the people associated with and benefited from the computer system.