In linguistic there are various types of movement which affects either heads or maximal projections. Wh-movement is an important phenomenon in a language. It is based on government and binding theory. This is a transformational approach of the theory of universal grammar which was developed by Noam Chomsky in 1980s. It is also called as Principles and Parameters theory as it accepts that all languages have universal structural principles together with various parameters on a language-specific basis. According to this theory Universal grammar has two components that are levels of representation and system of constrains. A language can be represented by different levels. First one is mental lexicon which stores different words then predicates which encode their semantic relationship by assigning theta-roles. The lexical items are arranged at D-structure. X-bar theory regulates the position of specifiers adjuncts and complements around a head X within a phrase XP.
The term Wh-movement originates from early Generative Grammar of 1960s and 1970s and used as reference to the transformational analysis. The Wh-expression appeared in its canonical position at deep structure and then moved leftward out of that position to land its derived position at the front of the sentence/clause at surface structure.
INTRODUCTION TO LINGUISTICS & PHONETICS - WH- Movement