Computer Science: the body of knowledge surrounding computers and related technology gained through systematic inquiry
Computer Science is a discipline which involves the study of computers and computations; and has theoretical, experimental, and design components including algorithms, programming languages, system development, computer hardware, and networking.
Computer Science is a body of knowledge concerned with computers and computations, which focuses on information transmission and manipulation. It includes theories for understanding computer hardware, programmes and systems; experimental methods for the development and testing of computational concepts; and design methodology, algorithms, and tools for their practical realisation.
Computer science is the study of models, their representation (usually in some electronic format), and their effects on the real-world processes from which those models are developed.
Computer Science is an art of computational theory, which is basically a science dedicated to develop, analyze, or evaluate new methods or algorithms to solve practical problem using automatic computers. Computer science has the characteristics of science, also it has some characteristics of engineering, which means most research results can be converted to commercial products in a short period, also which means in some cases, finding a reasonable solution for a specific situation is more important than finding a in applicable general or optimal solution.
Computer Science is, simply put, the study of computation. The study of anything that lends itself to a computational model is a study in Computer Science. The most fundamental concept of the discipline is the algorithm. An algorithm is a precise sequence of instructions. For example, there is a precise sequence of instructions one can follow to have a VCR tape a show at midnight. A computer program is an executable algorithm. After the algorithm, the next most fundamental concept in Computer Science is the data structure. A data structure is an abstract representation of an entity. For example, if a computer program is going to execute an algorithm to determine the shortest route between two cities, a representation (data structure) of a map needs to be designed and implemented.
In the words of Allen Newell and Herbert A. Simon (ACM Turing Awards Lecture, 1975):
Computer science is an empirical discipline. We would have called it an experimental science, but like as- tronomy, economics, and geology, some of its unique forms of observation and experience do not fit a narrow stereotype of the experimental method. None the less, they are experiments. Each new machine that is built is an experiment. Actually constructing the machine poses a question to nature; and we listen for the answer by observing the machine in operation and analyzing it by all analytical and measurement means available. Each new program that is built is an expermient. It poses a question to nature, and its behavior offers clues to an answer. Neither machines nor programs are black boxes; they are artifacts that have been designed, both hardware and software, and we can open them up and look inside. We can relate their structure to their be- havior and draw many lessons from a single experiment. We don't have to build 100 copies of, say, a theorem prover, to demonstrate statistically that it has not over- come the combinatorial explosion of search in the way hoped for. Inspection of the program in the light of a few runs reveals the flaw and lets us proceed to the next attempt.
Read the full paper (ACM Communications, March 1976) -- Highly recommended.