Series 26 · 14 Parts· 1h 21m

Modernization Glossary & Definitions

Plain, citable definitions of the core modernization terms — legacy systems, refactoring, microservices, the strangler pattern, and more.

Start reading · Part 1

Contents

01 Brownfield vs Greenfield Development: Definition 6 min read Brownfield development builds on an existing system and its constraints. Greenfield starts from scratch with no prior code. Most enterprise modernization is brownfield.
02 Digital Transformation: Definition 4 min read Digital transformation is the use of digital technology to change how a business operates and delivers value — often gated by the legacy systems underneath it.
03 Legacy Code: Definition 6 min read Legacy code is code that is hard to change safely — typically because it lacks tests and the knowledge behind it has left — regardless of how old it is.
04 Legacy System: Definition & Examples 6 min read A legacy system is business-critical software that has become hard to change safely — defined by the gap between what the business needs and what the system can deliver, not by age.
05 Lift-and-Shift (Rehosting): Definition 6 min read Lift-and-shift, or rehosting, moves an application to new infrastructure with little or no change to its code. It is the fastest modernization move and the least transformative.
06 Mainframe: Definition 4 min read A mainframe is a large, high-throughput computer built for reliability and transaction volume — still running core banking, insurance, and government workloads decades on.
07 Microservices: Definition 6 min read Microservices are an architectural style that builds an application as a set of small, independently deployable services, each owning one capability and communicating over a network.
08 Monolithic Architecture: Definition 6 min read A monolithic architecture builds an application as a single deployable unit, where all the code ships together. It is simple to run but harder to scale and change as it grows.
09 Re-Architecting: Definition 6 min read Re-architecting changes the fundamental structure of an application, its components, boundaries, and how they interact, while preserving what the system does for the business.
10 Refactoring: Definition 6 min read Refactoring is improving the internal structure of code without changing its external behavior — making it easier to understand and change while keeping what it does the same.
11 Refactoring vs Rewriting: Definition 6 min read Refactoring improves existing code in small, behavior-preserving steps. Rewriting replaces it with new code. The choice is mostly about risk, and rewrites concentrate it.
12 Replatforming: Definition 6 min read Replatforming moves an application to a modern runtime or managed platform with targeted changes — more than lift-and-shift, less than a rewrite — to gain platform benefits.
13 Software Modernization: Definition 6 min read Software modernization is updating aging software — its code, architecture, or platform — so the business can keep changing it safely, without replacing what already works.
14 Strangler Fig Pattern: Definition 7 min read The strangler fig pattern modernizes a system by building the new one around the old and shifting traffic gradually — replacing it piece by piece instead of in one big-bang cutover.