In the early days of computing, the development process was relatively unstructured and informal, lacking procedure and hence occasionally resulting in budget overruns, or generally low-quality software. Gradually over the years, this led to more structured approaches towards Software Development.

Software Testing

Software Testing is crucial because untested or poorly tested software can lead to significant losses. In 1996, the Ariane 5 rocket, designed by the European Space Agency (ESA) to launch satellites, exploded 37 seconds after liftoff, resulting in a $500 million loss. The failure was due to a software error in the navigation system, where inadequately tested software from the Ariane 4 was reused. This was caused by an overflow error when a 64-bit floating-point number was converted to a 16-bit signed integer, unable to handle Ariane 5's greater acceleration.

SDLC

Software Development Life Cycle, also known as SDLC, is a software development process, or more appropriately a framework under which various development processes are categorized, some examples of which include Scrum, and the traditional Waterfall method. All of these processes follow the core phases of SDLC, yet they are tailored to the specific needs of various types of projects.

The seven core phases of the Software Development Life Cycle are summarized as follows:

• Planning: Understand what needs to be built, and decide the project's goals;
• Analysis: Study the project's requirements and figure out what exactly is needed in terms of device or server specifications, cost requirements, and other project-specific factors.
• Design: Create a blueprint for what the project will look like and how it will function. Often a visual prototype is created for the application during this phase.
• Development: Write the actual code to build the software;
• Testing: Test the software thoroughly and make sure it works according to the requirements. Implement fixes if necessary. Quality Assurance and Testing fall into this category;
• Deployment: Release the software for users;
• Maintenance: Keep the software running smoothing by fixing issues and updating it as needed;

These phases don't necessarily need to be in the given order and may even overlap. For example, Testing is usually carried out during the Development phase, and Quality Assurance extends across the entire SDLC.

QA

Quality Assurance, known as QA in short, encompasses the broader process of making sure the development process proceeds efficiently with minimal errors while producing high-quality work and that the application conforms to the required standards. A QA Specialist has a role in every stage of development, ranging from planning to deployment plus maintenance of the software. Quality Assurance is more process-oriented, which means that it is more focused on, but not limited to, managing and improving the development process.

Quality Assurance includes defining standards and methodologies for development, planning test cases and test strategies, identifying and fixing defects, performing code reviews, and continuously monitoring and improving the development process.

On the other hand, (Software) Testing is a subset of Quality Assurance, more focused on executing tests to identify bugs, errors, or defects in the software. Testing aims to ensure that the features are working correctly according to the requirements.