-These environments must model the target systems, and they must be as close as is practical to those target systems. That doesn't mean you need to make exact copies of expensive production environments but you do need to have models of production environments that test enough of the pieces your code will come in contact. Having models that mirror production systems means you'll be less likely to introduce changes that have unintended consequences. You'll give yourself some comfort in knowing that the changes you enact in these models will be the same changes that will appear on the target system.
+These environments must model the target systems, and they must be as close as is practical to those target systems. That doesn't mean you need to make exact copies of expensive production environments but you do need to create models of production environments that test most of the pieces your code will come in contact. Having models that mirror production systems means that when you move your code to production you'll introduce fewer changes with unintended consequences. Your changes will have already existed in a production-like environment. You can take comfort in knowing that the changes you enact in these models will be the same changes that will appear on the target system.