Computer Science

Computer Science is a field of study that has something, but not a whole lot, to do with the things we know of as "computers."

Definitions

Let's see how Computer Science fits in...

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.

What is automation / programming / scripting?

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.

What Computer Scientists Do

In case anyone asks you, computer scientists:

Architect large software systems, i.e., identify the components and their behavior and interaction (this requires skill and enormous experience)
Organize information into data structures so that it can be efficiently processed
Devise algorithms to carry out the specified behavior of the components (this is a creative, artistic process)
Express algorithms (this is called programming)
Validate algorithms (using formal proof and heavy mathematics)
Analyze algorithms (usually to determine whether they satisfy efficiency constraints)
Test code (to increase confidence that a system meets its specification)

Subject Areas

For what it's worth, the ACM identified these 14 subject areas in Computer Science way back in 2001.

Discrete Structures (DS)
Programming Fundamentals (PF)
Algorithms and Complexity (AL)
Architecture and Organization (AR)
Operating Systems (OS)
Net-Centric Computing (NC)
Programming Languages (PL)
Human-Computer Interaction (HC)
Graphics and Visual Computing (GV)
Intelligent Systems (IS)
Information Management (IM)
Social and Professional Issues (SP)
Software Engineering (SE)
Computational Science and Numerical Methods (CN)

Exercise: Has anything changed? Can you think of recent trends in computing that might warrant another category?

More Subject Areas

Here's a more expanded list of things one can study 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 "get" the following concepts. Note that not many of these are specific to desktop or laptop or mainframe 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 Systems

The term software system is often used in place of the term "program" to emphasize the fact that most programs do not have a single set of inputs fed in at the beginning and a single set of outputs on termination. Instead many programs are built up from many relatively independent components and interact with users. 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 run in cars, aircraft, mobile phones, 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.

Related Fields

Computer science borrows from, and touches, a whole lot of other fields, including

Linguistics (probably the closest relative)
Biology (computational biology, biological databases, etc.)
Psychology (we'd like computers to think like us, and perhaps understand us)
Electrical Engineering (because face it, electronic components make good computing devices!)
Mathematics (especially Discrete Math, Game Theory, etc.)
Education (because both fields are concerned with knowledge representation and learning)
Philosophy (especially Logic, Epistemology)
Economics (think markets!)
Sociology (computers in society, social networking, Second Life and other virtual environments)