What is Legacy Software?

Pre-requisites:Software Engineering

Software is the product with the set of instructions, programs used to operate the computer and to perform the specific tasks. The programs will execute within a computer of any size and architecture.Software is a program or set of programs containing instructions that provide desired functionality. And Engineering is the process of designing and building something that serves a particular purpose and finds a cost-effective solution to problems. 

Legacy Software

The older programs which are developed decades ago that are still in use by performing modifications in order to meet the business requirements. The rapid increase of such systems may cause the risk to the larger organizations  as they may require outdated hardware and operating system.

Many legacy systems remain supportive to core business functions and are important to  business. Hence, legacy software is characterized by longevity and business criticality. 

Sometimes the additional characteristic that is present in legacy software is poor quality. Legacy systems some times have inextensible designs, convoluted code, testcases and result that were never archived, a poorly maintained change history, lack of support and documentation make it difficult to troubleshoot the issues and leaving the system to security threats and the list can be quite long. 

Just think about the case if we encounter a legacy software that exhibits a poor quality, as it support core business functions and are important to business, so they should undergo some changes to meet the needs of its users and run reliably. As time passes they needs to be evolved for the following reasons:

• As the technology is emerging people are looking for the personalized systems especially the working professionals because the latest software may introduce some required specifications in which the older one is lagging.
• It might not be compatible even if we use speedy modern systems with the older software.
• Software must be re-architected to make it capable of working within a network environment. 
• To fix the security issues which are found everyday, we need to change the software.
• Nowadays software is used in every industry like education, industries, healthcare, entertainment, retail, transportation, so by improving the software every industry will be benefitted.

The goal of modern software engineering is, building new software systems from old ones and make them interoperable and cooperate with each other, and also make them secure and more efficient. Sometimes the legacy software is treated as necessary but, with a limited capacity and simultaneously they are replaced by the newer systems.