Gecko is the name of the layout engine developed by the Mozilla Foundation. It was originally named NGLayout.
Gecko is used in many applications, including a few browsers, such as Firefox, Mozilla Suite, Camino, etc. (for complete list, please refer to Wikipedia's article on Gecko.) Products using the same version of Gecko have identical support for standards.
Versions of Gecko
|Gecko version||Application based on it|
|Gecko 1.9 (under development)||Firefox 3.0|
|Gecko 1.8.1 (under development)||Firefox 2.0|
|Gecko 1.8||Firefox 1.5, Thunderbird 1.5, SeaMonkey 1.0|
|Gecko 1.7||Firefox 1.0, Thunderbird 1.0, Nvu 1.0, Mozilla Suite 1.7|
|older versions of Gecko match the Mozilla Suite versions|