Computer Science is a field of study that has something, but not a whole lot, to do with the things we now call computers.
Definitions
Wikipedia’s Definition, as of 2015-01-01:
Computer science is the scientific and practical approach to computation and its applications.
My definition:
Computer Science is the theory and practice of computation,
algorithms, software systems, data organization, knowledge representation,
language, intelligence, learning, and consciousness.
A shorter definition, relating it to other broad fields of study:
Philosophy
The search for fundamental truths of the universe using logic (reasoning).
Mathematics
Reasoning on a formal basis (symbol manipulation).
Computer Science
The science of automating the reasoning process.
More buzzwords:
Computational Procedure
A step-by-step process for solving a problem described by a finite number of steps, where the execution of each step takes a finite amount of time. Steps can be of the form “go to step number n” so the process need not terminate.
Algorithm
A computational procedure which terminates regardless of its input.
Program (or Script)
An expression of a computational procedure in some language.
Exercise: Has anything changed? Can you think of recent trends in computing that might warrant another category?
More Subject Areas
Here’s a finer breakdown of subject areas within computer science:
Algorithms
Artificial Intelligence
Compilers and Interpreters
Computation Theory
Computer Architecture
Computational Complexity
Computational Geometry
Data Mining
Data Structures
Databases
Decision Support Systems (Knowledge-Based Systems)
Distributed, Parallel, and Cluster Computing
Digital Libraries
Graphics
Human Computer Interaction
Information Theory
Machine Learning
Modeling in Science, Engineering, and Finance
Multiagent Systems
Multimedia
Natural Language Processing
Networks and Internets
Neural and Evolutionary Computing
Numerical Analysis
Operating Systems
Programming Languages
Real-time Systems
Robotics
Scientific (Numeric, Symbolic) Computation
Search and Information Retrieval
Security (including Cryptography and Cryptanalysis)
Software Engineering
Virtual Reality (and Virtual Worlds)
Vision and Pattern Recognition
Visualization
Recurring Concepts
Computer scientists need to understand the following concepts. Note that these are not specific to computers that have keyboards and monitors.
Automation
Binding
Communication
Complexity
Consistency and Completeness
Efficiency
Evolution
Formal Models
Levels of Abstraction
Ordering in Space
Ordering in Time
Reuse
Security
Tradeoffs and Consequences
Kinds of Software
People use principles form computer science to create lots of
different types of systems.
Here’s a rough list of (overlapping) software system categories:
Information Systems that create, store, retrieve, manipulate, present, and destroy information (such as in databases).
Technical Systems such as control equipment in telecommunication, military or industrial production.
Embedded Real-time Systems which deal with physical sensors and actuators; you see these most often in run in cars, aircraft, appliances, etc.
Distributed Systems which contain many different physical computers connected via some network.
System Software, which is the low level code for operating systems, database systems, and user interfaces.
Application Software like games or word processors, which run on desktops, laptops, and mobile devices.
Related Fields
Computer science borrows from, and touches, a whole lot of other fields, including:
Wikipedia has a list of famous computer scientists. If you want to read about some of these people, don’t skip Alan Turing and Grace Hopper. Also find out about Donald Knuth and Alan Kay.