Pidgin languages sometimes form in contact situations where a means of communication is urgently needed between groups lacking a common code. They are typically less elaborate than any of the languages involved in their formation, and in comparison to those, reduction characterizes all linguistic levels.
The process is relatively uncommon, and the life span of pidgins is usually short – most disappear when the contact situation changes, or when another medium of intergroup communication becomes available. In some rare cases, however, they expand (both socially and structurally), and may even nativize, i. e. become mother tongues to their speakers (when they may be re-labelled “creoles”).
Pidgins are severely understudied, and while they are often mentioned as precursors to creoles, few linguists have shown a serious interest in them. As a result, many generalizations have been based on extremely limited amounts of data or even on intuition. Some frequently occurring ones is that pidginization is a case of second language acquisition, that power and prestige are important factors, and that most structures are derived from the input languages. My work with pidgins has led me to believe the opposite to be true in these cases: pidgins form through a trial-and-error process, where anything that is understood by the other party is sanctioned, this process is one of collaborative language creation (rather than one involving one group of teachers and one group of learners), and much of what finds its way in the resultant contact language do so independently of what the creators spoke prior to their encounter.
As for theoretical implications, pidgins may shed light on which features in traditional languages are necessary for communication, and which are superfluous from the point of view of pure information transmission.