This article is part of SHARE’s intro to the mainframe series. Read the articles on CICS, Automation, Catalogs, and HSLAM. If you would like to contribute to this series, please reach out to editor@share.org.
For a programming language that quietly runs the financial heartbeat of the modern world, Common Business Oriented Language (COBOL) is surprisingly misunderstood. Many early‑career technologists have never seen it. Others know it only through stereotypes: green screens, all‑caps code, and a vague sense that it belongs in a museum. Yet COBOL remains one of the most widely deployed, business‑critical languages in existence.
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What Is COBOL?
If you’re building a career in technology, especially on the mainframe, being clued in on COBOL is a cornerstone requirement: it is the programming language that has shaped enterprise computing for over 65 years and still powers most systems that matter. In fact, a recent survey suggested a global COBOL footprint of 250 billion lines of code —another survey estimating it was even higher still. The COBOL juggernaut keeps on rolling. Let’s consider why:
What Does COBOL Look Like?
COBOL’s defining characteristic is readability. Unlike languages that prize brevity or syntactic cleverness, COBOL was designed so that business logic could be understood by people who weren’t computer scientists. That was deliberate — in 1959, there was no such thing as a computer scientist. That clarity and simplicity is still its superpower.
A typical COBOL statement reads almost like structured English. As an example — let’s use banking — a simple business process (to manage customers trying to withdraw more than they in their account) might look like this:
If account-balance < withdrawal-amount
perform process-insufficient-funds-action
else
subtract withdrawal-amount from account-balance
end-if
Even if you’ve never written a line of COBOL before, the intent is obvious, and the meaning is clear. COBOL was built to express business logic directly, without requisite layers of abstraction or intellectual swagger. For developers new to the language, readability dramatically shortens the learning curve. For organisations, it reduces risk and improves maintainability.
Why Was COBOL Built?
Many modern languages began life as academic experiments or general‑purpose tools. COBOL was engineered for one purpose: business computing. Its data types, arithmetic precision, file handling, and transaction‑oriented constructs reflect the needs of organisations that must process high‑volume, high‑integrity workloads.
This business‑centricity is a major reason COBOL has endured. When you need to calculate interest to several decimal places, reconcile millions of daily transactions, or ensure payroll completes accurately and on time, you want a language that was built for that purpose. COBOL’s design choices still align with the operational realities of banks, insurers, retailers, and governments, which is why it still powers big business.
What Are COBOL’s Strengths?
One of COBOL’s most overlooked strengths is its portability. COBOL applications have moved across hardware generations, operating systems, and compiler versions for decades. From mainframes to distributed servers to cloud environments, COBOL has evolved and adapted without requiring organisations to rewrite their core business logic.
This portability and compatibility are a foundation of why COBOL systems remain so prevalent. When a language can survive multiple waves of technological change, it becomes a long‑term asset rather than a liability. Modern COBOL compilers continue this tradition, enabling organisations to deploy COBOL applications wherever their strategy demands.
Evolved and Innovated: What COBOL Actually Looks Like Today
If your mental image of COBOL involves monochrome terminals and fixed‑format code, it’s time for an update.
Modern COBOL:
- supports mixed- and lower‑case code and free‑format syntax,
- integrates with APIs, web services, and modern UI frameworks,
- runs under z/OS, and in containers, cloud platforms, and hybrid environments,
- fits easily into contemporary DevOps pipelines
In other words, COBOL has evolved alongside the platforms it runs on. Nobody drives a Model T Ford any longer, we all use smart phones today. Great inventions survive because they continue to evolve over time. The COBOL of today is a far cry from the dusty photographs of its early years. Yet some of those cliched perspectives pervade, so let’s set the record straight — here are a few COBOL myths, busted:
Myth: COBOL is written in ALL CAPS and verbose.
This was true when punch cards ruled the earth, but no longer. Developers can write COBOL in mixed case, lower case, or whatever style their standards dictate. Did you see the code snippet shared earlier? That’s valid COBOL syntax. The language has refined and streamlined.
Myth: COBOL is all old green screen systems.
COBOL is a language, not a UI. The green‑screen stereotype comes from old terminal applications, not from COBOL itself. Modern COBOL systems integrate with web front ends, REST APIs, mobile apps, and cloud‑native services. New interfaces might not be written in COBOL, but the back-end business processes still are.
Myth: COBOL is hard to learn.
COBOL was deliberately designed to be easy to learn by people with business domain knowledge. Its English‑like syntax and structured layout make it more approachable than most other languages. Developers routinely pick it up quickly.
The real challenge isn’t the language; it’s the scale and importance of the systems it powers, and the business processes encapsulated in its application code. Realistically, understanding decades-old applications comprising thousands of modules is difficult in any language. But the recent arrival of COBOL application discovery and understanding tools — often AI-infused — provides further support for those looking to re-learn and renew longstanding COBOL apps.
What Is the Future of COBOL? It Still Means Business
COBOL’s longevity is no accident. It has delivered because it continues to excel at what it was built to do. It has evolved, modernized, and adapted while preserving the clarity and reliability that made it indispensable.
For early‑career technologists, COBOL offers something rare: the chance to work on systems that genuinely matter. These systems move money, run governments, and keep industries functioning.
Understanding COBOL means engaging with the foundations of modern enterprise computing and strategizing how it can support the future. The future of the mainframe includes COBOL.
Learn More About COBOL
Derek Britton is a renowned technology and marketing leader, advisor, and commentator. Britton is widely published on topics such as mainframe, COBOL, application modernization, AI, IT skills, and marketing strategy, and was founding chair of the COBOL Working Group at the Open Mainframe Project.
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