What is classed as Legacy Infrastructure?
Legacy infrastructure refers to older systems, hardware and technology implementations that have been used over a long period of time within an organisation/industry and whilst effective and reliable at one point, they have become outdated, inefficient and/or difficult to maintain. However, just because a system is classed as 'legacy' this does not mean that is it nonfunctional. It could simply mean, it is an older system that still functions as originally intended but has been built with obsolete technologies and/or according to outdated software development techniques.
Legacy infrastructure components can still function and are still used in many organisations even though they are outdated. This is generally because these systems have underpinned certain workflows and operational processes for significant periods of time and the perceived cost, time and resource requirements to change outweigh the benefits of change.