The Land Classification is a classification of Great Britain into sets of environmental strata, termed land classes, to be used as a basis for ecological survey, originally developed by the Institute of Terrestrial Ecology (ITE) in the late 1970s. The strata were created from the multivariate analysis of 75 environmental variables, including climatic data, topographic data, human geographical features and geology data. The Land Classification has provided a stratification for successive ecological surveys (the Countryside Survey of Great Britain), the results of which have characterised the classes in terms of botanical, zoological and landscape features. Additionally, the Land Classification can be used to stratify a wide range of ecological and biogeographical surveys to improve the efficiency of collection, analysis and presentation of information derived from a sample. There are three versions of the Classification available. 1. The 1990 version containing 32 classes, which was the first to classify all 240,000km squares in Great Britain (building on an earlier 1978 version based on a sample of squares only). 2. A 1998 version, when the Land Classification was adjusted to 40 classes as a consequence of the need to provide National Estimates (from Countryside Survey 2000) for habitats for Scotland in addition to GB as a whole. 3. In 2007, the Land Classification was adjusted once again, to 45 classes, as a consequence of the need to provide Wales-only estimates in addition to those for Scotland and GB as a whole (from Countryside Survey 2007).