Because of the generally low status of the Creole people in the eyes of European colonial powers, creole languages have generally been regarded as "degenerate", or at best as rudimentary "dialects" of one of its parent languages. This view, incidentally, is the reason why "creole" has come to be used in opposition to "language", rather than a qualifier for it; so that one would say "a French creole" (rather than "a French-based creole language"), or "the Papiamentu creole" (rather than "the Papiamentu creole language").
This prejudice was compounded by the inherent instability of the colonial system, which led to the disappearance of many creole languages due to dispersion or assimilation of their speech communities. Another factor that may have contributed to the longtime neglect of creole languages is that they do not fit the "tree model" for the evolution of languages, which was adopted by linguists in the 19th century (possibly influenced by Darwinism) and is still the foundation of the comparative method. In this model languages may evolve, split, or die out — but cannot ever merge.
All creoles start as pidgins, rudimentary second languages improvised for use between speakers of two or more non-intelligible native languages. Keith Whinnom (in Hymes 1971) suggests that pidgins need three languages to form, with one (the superstrate) being clearly dominant over the others. The lexicon of a pidgin is usually small and drawn from the vocabularies of its speakers, in varying proportions. Morphological details like word inflections, which usually take years to learn, are omitted; the syntax is kept very simple, usually based on strict word order. In this initial stage, all aspects of the speech — syntax, lexicon, and pronunciation —tend to be quite variable, especially with regard to the speaker's background.
However, if a pidgin manages to be learned by the children of a community as a native language, it usually becomes fixed and acquires a more complex grammar, with fixed phonology, syntax, morphology, and syntactic embedding. The syntax and morphology of such languages may often have local innovations not obviously derived from any of the parent languages.
Pidgins can become full languages in only a generation, as with Tok Pisin, which was born as a pidgin and became a stable language in a period of 90 years. Once formed, Creoles can remain as a sort of second, local standard, like the Crioulo of Cape Verde. Some creoles, like Papiamentu and Tok Pisin, have obtained recognition as official languages. On the other hand, some creoles have been gradually "decreolized" by conforming a parent language, usually as a result of continuing political dominance, and have become essentially dialects of the latter. This has happened a little in Hawai'i, and is one theory of the development of African American Vernacular English from Slave English.