Every company operates in a certain environment. An environment is defined as
- "The sum total of all surroundings of a living organism, including natural forces and other living things, which provide conditions for development and growth as well as of danger and damage"  It is the world around us. For a business its the world around business. Strategic management defines the micro and the macro environment. The micro environment in the environment a company operates it. The macro environment is the whole world a company environment is situated in.
The micro environment is the business world is defined as
- "Factors or elements in an organization's immediate area of operations that affect its performance and decision-making freedom "
The micro environment can be made up of competitors, distribution channels, customers, suppliers, potential incomers, general public, substitute products and providers of complementary products. Every micro environment has the potential of being completely different then the next. Micro environments can differ in size and the factors that are of importance. One can imagine that a company that drills for gold in the russian tundra operates in a completely different environment then a sheep milker in ethiopia. Different variables are of importance, is the gold company watching the current gold levels known in the earth, and the price of gold in the market, the goat milker has different variables that are important to his business; like the amount of rain that has fallen, competition of the neighboring village, etcetera.
The macro environment is made up of the political, economic, ecological, societal and technological landscapes which surround the business micro environment. This is also defined as
- "The major external and uncontrollable factors that influence an organization's decision making, and affect its performance and strategies. These factors include the economic factors; demographics; legal, political, and social conditions; technological changes; and natural forces" 
Environments not only differ in the variables that are of importance. In environments there is a certain dynamic. This dynamic is partially dependent on the level of linearity of the environment. Linearity means that events follow each other in a predictable pattern. Based on historical information it is possible to predict what will happen in the future. Environments that have a more non-linear nature are significantly harder to predict. Non-linearity in this sense means to which degree future events do not resemble past patterns and events. The level of predictability is linked to the level of uncertainty in an environment, the more uncertain, the more we dont know what will come next.
- "An identifiable element in the physical, cultural, demographic, economic, political, regulatory, or technological environment that affects the survival, operations, and growth of an organization" 
Environment factors are important to companies because they are able to affect their existence. Like in our life, were we live is a constant factor of importance to our existence. To a company, a customer base could be an important factor because it enables its existence. Change in environment factors might lead to a possible improvement or possible danger of existence. A war, though out of control of the average human being might severely affect a humans existence. Variables from the micro environment as well as factors from the macro environment can be important to a specific company or other entity living in this world.
In order to try to understand and to predict environment events a company needs to know which factors/variables are of importance in their respected micro environment and which factors from the macro environment might possibly affect their existence. Discovering environmental factors of importance however is not a one time exercise, environments change, not only on a micro level, but also on a macro level, out of control of a company. The composition of factors of importance will change depending on events and changes in the micro and macro environment. Changes in the environment can lead to completely new factors that come of importance, others might become obsolete. Depending on the dynamic of the micro/macro environment the exercise of discovering environmental factors of importance can become very hard, especially in a unstable and unpredictable environment with numerous interrelated environment factors. The more complex the environment the more difficult to discover key variables. Chaos/turbulence/complexity has a huge effect on the level of predictability in an environment and the possibility to discover key variables.
Methodologies have been defined from the field of strategic management to discover macro environment factors that might be of affect on a company's existence. Because these factors are important to a company's existence they highly influence the decision process. The discovery of succes factors in the environment on micro and macro level is a very important factor in strategic management.
- "Environmental scanning, econometric models (such as the Chase Econometric Service or the Wharton models based upon key environ- mental/economic variables), socio-political consulting services, and governmental affairs departments are but a few of the diverse approaches used to monitor and assess environmental impact on the industry and the firms comprising that industry" 
The http://en.wikipedia.org/wiki/PEST_analysis analysis tries is a model intended to scan the macro environment for important factors. http://en.wikipedia.org/wiki/PEST_analysis focusses on political, economical, social and technical factors in the macro environment. Differentiation's of this model exist to further identify important macro factors. An example of an extended PEST model is the PESTEL model. The PESTEL model also takes into account the environmental and legal factors in addition to the factors defined in the PEST model.
- Business Dictionary: http://www.businessdictionary.com/definition/environment.html
- The Business Dictionary: http://www.businessdictionary.com/definition/microenvironment.html
- Business Dictionary: http://www.businessdictionary.com/definition/macro-environment.html
- Business Dictionary: http://www.businessdictionary.com/definition/environmental-factors.html
- Identifying and using critical success factors: http://www.sciencedirect.com/science/article/pii/0024630184901638