Syntactic theory of Chomskyan orientation has recognized that syntactic dependencies can span only a limited portion of structure, and that apparent long-distance dependencies typically consist of a succession of local dependencies. This property of syntactic dependencies is called locality. This chapter focuses on the locality of filler-gap dependencies, quintessentially represented by the wh movement, and sketch a historical perspective on its development. The theory of barriers marks the first significant development in generativist theorizing about locality in syntax since the introduction of the Subjacency Condition. The binding-based filler-gap dependencies across islands never exhibit island effects. Relativized Minimality provides an immediate syntactic account of a variety of well-known locality effects. There are a number of empirical observations that can be taken to provide evidence for the size and location of locality domains. Syntactic operations, most prominently movement, must not be too local. This has come to be known as anti-locality.