1. Borrowing
This means taking words straight into another language. Borrowed terms often pass into general usage, for example in the fields of technology ("software") and culture ("punk"). Borrowing can be for different reasons, with the examples below being taken from usage rather than translated texts:
the target language has no (generally used) equivalent. For example, the first man-made satellites were Soviet, so for a time they were known in English as "sputniks".
the source language word sounds "better" (more specific, fashionable, exotic or just accepted), even though it can be translated. For example, Spanish IT is full or terms like "soft[ware]", and Spanish accountants talk of "overheads", even though these terms can be translated into Spanish.
to retain some "feel" of the source language. For example, from a recent issue of The Guardian newspaper: "Madrileños are surprisingly unworldly."