Gecko is being developed at mozilla.org. Gecko has been known previously by the code names Raptor and NGLayout. NGLayout originally meant "Next Generation Layout", but later came to mean "Netscape Gecko Layout".
Gecko offers a rich programming API that make it suitable for a wide variety of roles in Internet enabled applications, such as web browsers, content presentation and client / server. Primarily it is used for the Mozilla browser derivatives such as Netscape 6, but it is used elsewhere as well.
Products that use Gecko for the entire user interface via XUL: