Computer Science

Computer science is the scientific and practical approach to computation and its applications. Or simply The study of the principles and uses of the Computer.  A computer scientist specializes in the theory of computation and the design of computational systems.
Computing includes designing, developing and building hardware and software systems; processing, structuring, and managing various kinds of information like making systems behaves intelligently(Artificial Intelligence), Scientific research,etc., 
The field of computing includes computer engineering, software engineering, computer science, information systems, and information technology.

Computer

• A Computer is an electronic device used for processing and storing the data in binary form. The computer manipulates or processes the data in the form of set of instructions called "Programs". 
• In general, A program consists of bits and pieces of source code. A source code of a program is collection of instructions written by human readable computer language.
• A Programmer studies and develops the programs in sequence of steps called Algorithms. 

Computer Software  

• Computer Software or simply Software refers to one or more programs and data held in the storage of the computer. 
• A Software is a collection of computer programs and related data that provides the instructions for telling a computer what to do and how to do it. 
• software is a set of programs, procedures, algorithms and its documentation concerned with the operation of a data processing system.

Computer Programmer

A computer programmer/coder(Specialist in one area of programming) is a person who writes computer software. The term programmer can be used to refer to a software developer, software engineer, computer scientist. 

Computer Network

• A computer network or simply a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information. 
•  If  two devices are said to be in a network then one process in one device is able to send/receive data to/from at least one process residing in a remote device,.
• A Network is defined based on different aspects such as mediums, protocols, topology, scope,etc.,

User

A user is one who uses a computer or network service.