What Does Brownfield Mean?
Brownfield refers to the implementation of new systems to resolve IT problem areas while accounting for established systems. New software architecture must account for existing and running software.
A commonly used IT term, Brownfield was borrowed from the building industry, where brownfield land describes a geographical location where new buildings may be constructed after considering the area's established structures and services.
Techopedia Explains Brownfield
Brownfield development enhances traditional software engineering practices. Greenfield, or a blank slate, is considered the traditional target environment during software development. Brownfield extends the traditional software development plan to add context. Thus, the context of the IT system under construction and all system details are factored into any development practice prior to implementing improvements.
As recently as 2006, the IT industry has had more failure than success due to unexpected complexities related to the large scale delivery of software changes to customers, including risky and expensive brownfield development.