English is a very creative language which often uses semantic neologisms (a new meaning is given to an already existing word) and/or terminologization (a generic word is transformed into a new term in a special language).

Here are a few well-known examples* of terms that originally described only animals but which have taken on new meanings in the IT world:

	bug	An error in coding or logic that causes a program to malfunction or to produce incorrect results. [See Wikipedia for info on the history of this term]
	mouse	An input device with the following features: a flat-bottomed casing designed to be gripped by one hand; one or more buttons on the top; a multidirectional detection device (a ball, laser or optical device) on the bottom; and a cable or wireless connection to the computer.
	spider	An automated program that searches the Internet for new Web documents and places their addresses and content-related information in a database, which can be accessed with a search engine.
	watchdog	A hardware device that monitors system health and functionality through communications with the system software.
	worm	Self-propagating malicious code that can automatically distribute itself from one computer to another through network connections. A worm can take harmful action, such as consuming network or local system resources, possibly causing a denial of service attack.

In localization it is not always easy to find suitable equivalents for English neologisms. There is no rule, and choices are made on a term by term basis for each target language.

In some cases a calque is used, especially if the original metaphor is transparent (a mouse actually looks like a rodent and most languages opted for a literal translation, e.g. souris in French and Maus in German); sometimes the English terms enters the target language as a loanword (in Italian the device is called mouse); in other cases ad hoc solutions are found based on the most relevant features of the concepts represented by the English neologisms.
     

Licia Corbolante, Italian terminologist

* Examples from Terminologia etc.; definitions from the Microsoft terminology database.
   You can search Microsoft terminology in the Microsoft Language Portal.