Computer science, abbreviated as "compsci", is (surprise-surprise) a science studying computers. The term is pretty wide, a lot of it covers very formal and theoretical areas that neighbor and overlap with mathematics, such as formal languages, cryptography and machine learning, but also more practical/applied and "softer" disciplines such as software_engineering, programming hardware, computer networks or even user interface design. This science deals with such things as algorithms, data structures, artificial intelligence and information theory. The field has become quite popular and rapidly growing after the coming of the 21st century computer/Internet revolution and it has also become quite spoiled and abused by its sudden lucrativity.
Notable fields of computer science include:
Computer science also figures in interdisciplinary endeavors such as bioinformatics and robotics.
In the industry there have arisen fields of art and study that probably shouldn't be included in computer science itself, but are very close to it. These may include e.g. web design (well, let's include it for the sake of completeness), game design, system administration etc.
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