Suitability analysis
Suitability Analysis is the process and procedures used to establish the suitability of a system – that is, the ability of a system to meet the needs of a stakeholder or other user. Before GIS (a computerized method that helps to determine suitability analysis) was widely used in the mid to late 20th century, city planners communicated their suitability analysis ideas by laying transparencies in increasing darkness over maps of the present conditions. This technique's descendant is used in a GIS application called multicriteria decision analysis. In the 1960s, a mechanism called the ecological inventory process was developed  to document existing surrounding land conditions to help inform the analysis for the land in question. These mechanisms were computerized upon the advent of computers due to inefficiencies in the methods, such as the inability to overlay a large number of transparencies. In order to feed a growing population that is pushing on the ability to extensively farm, suitability analysis is becoming more necessary to utilize the most productive land to its fullest potential, matching the needs of the plants more carefully to the existing assets in the environment. This technique is known as precision farming. Suitability analysis can also  be used to track and label potential hazards, like earthquakes, contamination, or even crime. It can also be used to locate advantageous locations for commercial centers. Suitability in GIS context. Suitability analysis in a GIS context is a geographic, or GIS-based process used to determine the appropriateness of a given area for a particular use. The basic premise of GIS suitability analysis is that each aspect of the landscape has intrinsic characteristics that are to some degree either suitable or unsuitable for the activities being planned. Suitability is determined through systematic, multi-factor analysis of the different aspects of  the terrain. Model inputs include a variety of physical, cultural, and economic factors. The results are often displayed on a map that is used to highlight areas from high to low suitability. A GIS suitability model typically answers the question, "Where is the best location?" — whether it involves finding the best location for a new road or pipeline, a new housing development, or a retail store. For instance, a commercial developer building a new retail store may take into consideration distance to major highways and any competitors' stores, then combine the results with land use, population density, and consumer spending  data to decide on the best location for that store. Possibility Space. The Possibility Space is a framework that allows for the analysis of all possible consequences and benefits of a suitability analysis. This is created through geometrical data analysis conducted in real time with technological land mapping, allowing for the development of multiple combinations of suitability. Physically it is a visual interactive database that allows for a holistic composition of suitability. Results. When suitability analyses are done, several different usability options may be found for the same section of land. This can be advantageous or limiting. If the land  is found suitable for two or more uses that can be combined, the land uses are found compatible. An example of this may be a building with businesses on the bottom floor with residences on upper floors. Compatible land uses result in a win-win development; a need for more commerce is met while meeting a need for more housing, while also keeping people on the street all day, thereby reducing the probability of crime. Conflicting land use occurs when a piece of land can be used only for one use or the other. This is exemplified by a piece  of land that can either be used as agricultural land or developed into a housing tract—should the land be developed, it can no longer be used for agriculture. The suitability analysis comes back into play here by helping planners prioritize which need is greater (in the case of the example, is housing or agricultural land more necessary in light of economic or demand pressure).