Wh-movement (or wh-fronting or wh-extraction or long-distance dependency) is a mechanism of syntax that helps express a question (or form a relative clause). Sentences or clauses containing a wh-word (interrogative word) show a special word order that has the wh-word (or phrase containing the wh-word) appearing at the front of the sentence or clause, e.g. Who do you think about?, instead of in a more canonical position further to the right, e.g. I think about you.